• Eurotunnel says 1,500 migrants try to storm Channel Tunnel

• Sudanese migrant dies in new assault as Calais crisis continues

• Theresa May chairs meeting of Government's Cobra committee

• She urges security upgrade and says 'number of migrants' enter UK

• Operation Stack under Government review as lorries queue on M20

• Prime Minister says he has sympathy for British holidaymakers

• Thursday latest: Calais migrants undeterred by Calais security blitz

Latest

That concludes our live rolling coverage. Our Home Affairs Correspondent David Barrett reports that the Government is facing calls for tough action to resolve the Calais crisis amid fears that up to 150 illegal immigrants are reaching Britain each night.

As Theresa May, the Home Secretary, led an emergency Cobra meeting Wednesday the Channel Tunnel operators turned on the British and French government for failing to act.

And in a further deepening of the crisis, Mrs May faced a serious set-back in the courts as senior judges banned a fast-track detention scheme used to process migrants who reach Britain and claim asylum.

The key ruling means it will be much harder for the Government to remove migrants, as it emerged more than 300 foreigners detained under the scheme have already had to be freed by the Home Office.

Britain’s borders are expected to come under renewed attack later on Thursday as French trade unions are poised to launch further wildcat strikes, leading to queues of lorries which are sitting targets for stowaways.

Thank you, good night.

18.20 Chief executive of Eurotunnel describes the situation in Calais as "like a systematic invasion"

Eurotunnel chief executive Jacques Gounon described the situation at the Calais rail-head as like a "massive systematic invasion" that was nonetheless "organised" by migrants seeking to reach Britain every night.

"All of the necessary measures will be taken to protect the tunnel with regards to stowaways reaching Britain.

"This is not a problem of quality (of the migrants' skill at breaching security), it is a problem of quality."

17.30 Calais residents furious at lack of government action to stop the migrant crisis, reports The Telegraph's Rory Mulholland in Calais

"Calais is suffocating. The tourists have stopped coming here because all they see on the telly is stories about migrants and they are afraid to come," said Gilles Duvauchelle, the owner of Le Bounty café in the town centre.

Several customers at the bar nodded in agreement, with one woman saying that Britons used to come in large numbers to stock up on wine and French food in the hypermarkets on the edge of town. But now they have dwindled to a trickle, she said.

"The government is incompetent," said Mr Duvauchelle. "When migrant camps build up in Paris they move them on. But when they're here in Calais they don't give a damn," he said.

He said he was a truck driver for 20 years and is shocked at what lorry drivers have to put up with now if they arrive in Calais.

"They get attacked, they get migrants climbing in and the police can do little to stop it because they are overwhelmed by the numbers."

17.20

16.45 "Several dozen migrants probably made it to Britain," says French police chief

Several dozen migrants probably managed to make it to the UK over the past couple of nights when hundreds broke into the Eurotunnel terminal, a police union spokesman told the Telegraph.

"There's not much a few dozen police officers can do when faced with hundreds of migrants. We just try to make sure they don't get hurt when climbing on board trains or trucks," said Claude Verri of the UNSA union.

He was speaking on a bridge overlooking hundreds of lorries lined up as they waited to be searched by police and then board trains to take them through the nearby Channel Tunnel.

It was in this area that over the past two nights hundreds of migrants broke through the fences supposed to keep intruders out of the terminal area.

"They try to break in every night but it's been a whole lot worse over the last two nights, with hundreds pf them managing to do it," sais Mr Verri.

He said he believed it was only going to get worse in the coming weeks as more and more migrants arrive in the Calais area.

The officer said that faced with such overwhelming nunbers there was little police could do.

"It's like trying to swat moles. All we can do is take them out of the terminal area and then leave them there. And then five minutes later they can be back insde again."

On nights when large numbers of migrants try to break into the terminal, buses are laid on in the early morning to bring them aeay from the site and deposit them near Calais town centre.

16.25 Report of a badly injured Egyptian national, hurt after trying to stowaway on a Eurostar service at the Gare Du Nord

Paris' Gare Du Nord Eurostar terminal

16.20 Operation stack expected to last into the weekend

#OpStack #M20 closures remain in place btwn J8-11 coastbound & J9-J8 London-bound. #OperationStack expected to last into the weekend #alert — Kent Police (UK) (@kent_police) July 29, 2015

16.15: BREAKING - French media report that police numbers are being reinforced on the Calais side of the crossing

France's interior minister Bernard Cazeneuve announces 120 extra police officers for the Calais terminal, according to BFMTV.

French radio station France Bleu also reports that four Sudanese migrants bound for Britain were intercepted by Gendarmes on the A7 road to Calais. A Sudanese migrant was earlier killed by a lorry leaving the tunnell on the UK side of the crossing.

16.00: Keith Vaz 'watched 148 migrants' successfully enter the UK illegally

Labour MP Keith Vaz, who chairs the Home Affairs Select Committee, said he had witnessed 148 migrants successfully make the journey illegally to England yesterday.

Mr Vaz said Britain and France need to work together to solve the problem and he commended the Government for committing funds.

But he told BBC News: "At the end of the day, I'm afraid, sending an extra 140 police officers into Calais is not going to solve the problem.

"Every single day more than 1,500 migrants are trying to storm the Channel Tunnel into the freight area.

"I went to Kent yesterday and I saw 148 of them who had made the journey and who were delighted because they had been successful in coming here, having evaded all this security, they actually managed to come here so unless you do two things we are not going to solve this crisis."

Mr Vaz said migrants need to be returned to their country origin once they have no right to stay in France, adding the EU has a responsibility to help Greece and Italy by stopping people crossing the Mediterranean from North Africa.

He also said migrants want to come to Britain as they believe they can work illegally.

Prime Minister David Cameron must meet French president Francois Hollande when he returns from Asia and explain how important the issue is to Britain, France and the EU, Mr Vaz added.

15.29: 'Government should have got onto this months ago'

Interim Labour leader Harriet Harman has explained what she thinks the Government and French authorities should be doing:

This is not just a problem in Calais now, it is a major problem in Kent as well. As long ago as nine months ago we were pressing the Government that they needed to get on to this and sort this out and in fact I raised this with the Prime Minister in the House of Commons earlier last month.

"The Government have failed to get it sorted out and as a result people who have worked all year for their holidays are now stuck in traffic jams without information and it is having a big economic impact on the road haulage industry too.

"What the Government should be doing is getting the French to process the 3,500 to 4,000 people who are massed at Calais and need to be documented.

"Either they are genuine asylum-seekers who should be given asylum or they should be deported. The Government should have got on to this months earlier."

15.22: Video of Theresa May after Cobra meeting

After Home Secretary Theresa May announced urgent measures to protect the Eurotunnel from more migrant activity (see 13.28 update), here's footage of her outlining the proposals:

15.10: Gurkha soldiers 'should protect UK border'

Kevin Hurley, a former head of Scotlan Yard's counter terrorism branch and the police and crime commissioner for Surrey, has called for Gurkha soldiers based at Shorncliffe barracks in Folkestone to be deployed to protect Britain's border:

I am increasingly frustrated by the huge numbers of illegal migrants who jump out of the backs of lorries at the first truck stop - Cobham Services in Surrey - and disappear into our countryside. There were 100 in the last month alone.

"With ongoing cuts to police funding, year on year, it is hard enough to maintain regular policing, let alone the new demands around child sexual exploitation, cyber crime and domestic abuse, without also having to deal with desperate, homeless and penniless migrants as well.

"Of course, I realise that the root cause of this tragic migration is the appalling environments these people leave behind.

"They take enormous risks because they can see no other alternative. But, while the UK and French governments decide their next prevention strategy we, the British police, have to deal with the immediate problem.

"The Gurkhas are a highly respected and competent force, and are just around the corner. They could help to ensure that our border is not breached."

A driver climbs on his truck as he waits to cross the English channel (AP)

14.55: Death toll of migrants desperate to reach Britain

According to the Calais Migrant Solidarity group, more than 30 migrants have been reported as having died while trying to reach Britain via the Channel Tunnel since the beginning of 2014. Here is a round-up of some of the cases:

June 26: An Ethiopian is killed near the tunnel as he tried to climb on board one of its lorry-carrying shuttles

July 7: Another migrant dies inside the tunnel between France and Britain

July 20: Three migrants die of burns suffered a few days earlier as they tried to enter the tunnel

July 22: A migrant drowns in Calais while trying to gain access to the tunnel

July 24: An Ethiopian migrant is struck and killed by a car on a highway near Calais

May 5: An Eritrean is killed after jumping from a lorry after he realised it was heading in the wrong direction. The same day, two other migrants drown in the port of Calais trying to reach a ferry terminal

May 23: An 18-year-old Sudanese man is crushed by the bus he was hanging to

August 13, 2014: The body of a young Asian woman is found at the base of a cliff near Boulogne-sur-Mer. A probe determined that she fell while trying to reach the beach to swim across the English Channel

April 5, 2014: The unidentified body of a migrant is found inside the tunnel, eight kilometres (five miles) from the French entrance

October 30, 2014: The body of a 25-year-old Indian migrant is found inside a Slovenian lorry. He and two other migrant companions had hoped to make it on to a ferry bound for Britain

14.39: 'World's biggest lorry park' continues until weekend

More bad news for motorists: Kent Police says Operation Stack - where freight traffic is parked on the M20 when cross-Channel crossings are disrupted - is expected to last into the weekend.

Sailings from the Port of Dover are continuing, with P&O Ferries running full services to Calais and DFDS operating a full schedule to Dunkirk and Calais.

The port said: "The port and the ferry operators are together working hard to serve all customers travelling to and from the continent. We apologise for any delays or inconvenience as a result of traffic congestion."

Here are some pictures people have posted on Twitter of how the "world's biggest lorry park" is looking this afternoon:

14.25: 'Crazy' scenes as migrants waited to storm tunnel

A British lorry driver has described how he witnessed a group of migrants waiting to storm the Channel Tunnel in Calais on Tuesday night.

Les Muffett, from Witham, Essex, arrived at the Eurotunnel terminal in northern France just hours before hundreds of migrants successfully breached the fences.

The 56-year-old said: "When I got into Calais (the migrants) were everywhere, they were walking around like passengers.

'You can't confront them. They carry knives. All you can do is stay in the lorry, lock the cab up and let them get on with it...' - lorry driver Les Muffett

"When we drove out the compound all these people were outside the gates waiting to come in. It was crazy. It's the first time I've seen that myself. It's the worst it's been."

The married father of one has been a lorry driver for over 30 years and drives from Essex to the Italian city of Milan every week.

"So far I've been lucky. I haven't had any migrants in the lorry," said Mr Muffett, who works for Youngs Transport Ltd in Purfleet, Essex.

"It's scary because we don't know what will happen. A friend of mine was sitting in the queue and they cut his lorry open and got in.

"You can't confront them. They carry knives. All you can do is stay in the lorry, lock the cab up and let them get on with it. You can't put yourself in danger. We've got families at home and we've got to think about that."

Migrants wait near a motorway leading to the ferry port to cross the English channel in Calais (AP)

14.12: Eurotunnel 'facing systematic and massive invasions'

Jacques Gounon, the chairman of Eurotunnel, told French radio station France Info the company had invested "considerable sums" to shore up security. He said:

This isn't a case of a passenger not paying for their ticket, we are facing systematic and massive invasions, maybe even organised ones.This is a problem of numbers, it's not a problem of quality, it's a problem of quantity.

"Regardless of the huge investment we have made and are continuing to make to protect the boarding paths, there's a problem of quantity (of policing) when you consider the size of the first trans-Channel operator which is the Channel Tunnel."

French police secure the road near a British lorry as HGVs queue to embark on shuttles at the Eurotunnel terminal in Calais (Reuters)

14.02: 'We can only drop migrants off a few hundred metres away'

"We are completely overwhelmed," a policeman patrolling the motorway to stop migrants trying to board Britain-bound lorries parked as they wait to enter the Channel Tunnel told The Telegraph's Rory Mulholland.

"It just gets worse and worse. At the Channel Tunnel terminal all we can do is pick them up and then drop them off a few hundred metres away. We can't lock them up," he said, declining to give his name as he was not allowed to speak officially.

Earlier, French interior minister Bernard Cazeneuve promised an extra 120 police officers would be sent to Calais to secure the Eurotunnel site from migrants desperately trying to reach Britain (see 11.36 post)

Migrants walk along the roadside while a French policeman secures the area as lorries queue in Calais (REUTERS/Pascal Rossignol)

13.55: Latest travel information for Eurotunnel passengers

Eurotunnel has issued these update on the latest with its services from both sides of the Channel:

From Folkestone, we're still experiencing a 01h on-site and working hard to reduce it. Thank you for your patience. ^SL — Eurotunnel LeShuttle (@LeShuttle) July 29, 2015

From France,we're running with up to 3 departures per hour with a disrupted timetable. Please accept our apologies for any inconvenience.^SL — Eurotunnel LeShuttle (@LeShuttle) July 29, 2015

13.43: 'This is about ensuring we get that security fencing up'

Mrs May said the Government was pressing for rapid installation of the new security fencing at Coquelles.

Asked if the military should be used, the Home Secretary said: "This is about ensuring we get that security fencing up, it's about working with Eurotunnel to ensure we have got the best measures in place."

She added: "The key thing is to make sure we have got the security right at Coquelles and ultimately actually the answer to this problem is to ensure we are reducing the number of migrants who are trying to come from Africa across into Europe, that we break that link between making that dangerous journey, as it often is for people, and coming to settle in Europe.

"We do that by working with countries upstream, the work we are going to be doing with the French on returning people to West Africa and also on dealing with the criminal gangs that are making a profit out of people's misery."

Mrs May said the Government was working "very constructively" with their French counterparts.

She added: "We are working very hard with the French authorities and also with Eurotunnel to ensure we are able to increase the security at the railhead at Coquelles so we don't see people coming through the tunnel.

"Every effort is being put into that, a number of measures are now being discussed that have come out of the Cobra meeting today."

Migrants on the tracks at Calais early today

13.35: Call for 'urgent' improvement in Calais security

Reporting on the Cobra meeting she chaired this morning, Theresa May said:

I know people living in Kent and British holiday makers and road hauliers are facing real issues. The meeting was focusing on making sure we are doing everything we can to reduce the disruption people are feeling.

"Last night, I had very good discussions with my French opposite number the interior minister Bernard Cazeneuve, we are looking at the disruption this is causing people, we are talking particularly on law and order and border security at Calais and Coquelles.

"What we are seeing at the railhead at Coquelles is, as we are putting extra security fencing in, there have been migrants particularly trying to get into the Eurotunnel and on to the trains before that security fencing is going up.

"One of the outcomes of the meeting today was some more urgent work with Government departments but also with Eurotunnel on further measures can be taken at Coquelles to prevent people from getting into the tunnel."

Mrs May said Operation Stack had also been reviewed, adding it was causing "real problems" for Kent residents.

She added: "The meeting has tasked the Department for Transport, working with Kent County Council and others, to find options urgently to ensure we can reduce that disruption."

Long queues on the M20 in Kent as part of Operation Stack (PA)

13.28: Migrants have reached Britain through Channel Tunnel

Some migrants have reached Britain through the Channel Tunnel, Theresa May said after a meeting of the Government's emergency Cobra committee. The Home Secretary did not say how many people had reached Britain over the last couple of days.

Speaking at the Home Office, she said: "A number of people have come through. We will be dealing with anybody's asylum claim in the normal way as we always do.

"But crucially what we are looking at now is improving security at the railhead at Coquelles, so we can ensure people are not trying to come through the tunnel.

"That means some urgent work in government but also with Eurotunnel, and Eurotunnel has a role to play here in the measures they themselves put in place to protect their trains."

13.18: Migrants 'will try to reach Channel Tunnel every night'

Our man in Calais, Rory Mulholland, has been speaking to migrants near the tunnel entrance. He has just met three young men from Syria on the side of the motorway beside the line of 10m line of trucks backed up waiting to get into the tunnel.

Jabba, a tour guide, Mohammed, a trained doctor and Ahmed, a carpenter. Jabba and Mohammed are both 27 and Ahmed is 35.

They said to me they had been among the people trying to get into the terminal last night

Jabba said: 'Last night there was a gate open so we went through. There were about 200 in my group, but I felt there was no chance so after a couple of hours I left again. In the morning the police chased us out with pepper gas.'

"Then I asked him 'will you try again?' and he said: 'Of course, we will try again every night.' They said live in a tent in the 'new jungle' a few miles from Calais and have been about three weeks.

"When I met them they were returning from an Aldi supermarket with provisions for the wait."

12.53 Calais crisis a humanitarian issue, says Farron

Tim Farron, the leader of the Liberal Democrats, has described the situation in Calais as "primarily a humanitarian one" as he says Britain must "accept our fair share of refugees".

If you don’t give people hope, they will resort to desperate measures. We are treating this as a security issue, but primarily it is a humanitarian one.

"We should be big enough to take a lead and accept our fair share of refugees, rather than expecting others to do it for us.

"There are genuine people who need our help, but equally there are people exploiting a desperate situation. The UK government must provide all the support it can to maintain a firm but fair approach at our borders.

"That means the UK needs to sign up to the EU asylum policy, but just moving in with force and building a bigger fence is not a solution.

"We must not lose sight of how desperate someone has to be to cling to the bottom of a lorry in a bid to get a better life."

French gendarmes question migrants in Calais on Wednesday (Reuters)

12.37 Lorries queued for 10 miles as police watch for migrants

Here's the latest on the situation in Calais from The Telegraph's Rory Mulholland:

A line of lorries parked on the motorway leading to the Channel Tunnel terminal stretches back around 10 miles. Cars appear to be advancing normally towats the Shuttle entrance.

"Police are positioned at intersections watching out for migrants trying to sneak on board the lorries bound for Britain, while others drive in patrol cars along the route.

"But there are only a few small groups of migrants at the moment walking in the fields along the motorway."

12.30: 'We must close Calais until French get a grip'

Ukip's immigration spokesman, the MEP Steven Woolfe, has written a blog for The Telegraph on why he thinks Calais needs to be closed down until the French "get a grip" - and why that is only the start of what needs to be done. You can read it here.

Migrants queue to receive their daily food distribution at a centre for migrants in Calais (Francois Mori/AP)

12.23: Lorries queue for miles on M20 in Kent

New pictures have just arrived of the incredible number of lorries queued up as far as the eye can see on the M20 in Kent as part of Operation Stack.

Kent Police confirmed the operation has been extended this afternoon and now means J8 to J11 coast-bound and J9 to J8 London-bound are closed.

Freight traffic is urged to join the queue at J8, using lane one, to secure an Operation Stack ticket (without one, Port of Dover staff will turn HGV drivers away).

12.14: Migrants tried to get into my car, says Nigel Farage

Here's video of Ukip leader Nigel Farage calling the crisis at Calais a "disaster" (adding to his previous comments - see 11.42 post), as he describes how he was surrounded by migrants recently when he was at the Eurotunnel terminal with people trying to get into his car:

12.08: Eurotunnel 'has blocked 37,000 migrants'

As it comes under increased pressure to do more to deal with the crisis, Eurotunnel has revealed its staff has blocked more than 37,000 people attempting to cross into the UK this year.

A spokesman for Groupe Eurotunnel, which manages and operates the Channel Tunnel, said that since the arrival of migrants in the area around Calais, it has invested more than 160 million euro (£113 million), including 13 million euro (£9.2 million) in the first six months of 2015, in physical resources - fences, cameras, infra-red detectors - and personnel.

He added: "These considerable investments have already been followed in the second half of the year with new fencing around the platforms. Security patrol staff has been doubled to reach 200 employees, including sniffer dog patrols.

"To support the efforts of law enforcement in the Calais area, Eurotunnel has also provided buses to the authorities to enable them to remove any migrants intercepted."

11.59: Eurotunnel accused of 'not making enough effort'

The French interior minister Bernard Cazeneuve has accused Eurotunnel of not doing enough in light of the "worsening situation" in Calais.

The letter from Mr Cazeneuve to Eurotunnel president Jacques Gounon is dated July 23 and was leaked to the French press.

It said: "In my analysis, the Eurotunnel group, which has jurisdiction of the security, hasn't made enough effort in light and proportion to the worsening situation.

"I would like you to have a further look at the human resources you are planning on dedicating to securing the site", he added, believing the company has cut its security staff by two-thirds since 2002.

He said: "In the same timeframe, the state has multiplied its resources by five, and... 350 members of the state security police force (CRS) and police officers work together every day to prevent intrusions."

Eurotunnel has said it has gone "beyond its contractual obligations" to protect the terminal in Coquelles, near Calais.

Bernard Cazeneuve (Getty)

11.54: Latest travel information for UK Eurotunnel passengers

11.50: 'This is affecting the whole of Europe'

The crisis at Calais is affecting the whole continent as the European supply chain is disrupted, according to Philip Gomm, from the RAC Foundation:

This has gone far beyond a minor matter confined to Calais and a corner of South East England. It is affecting people and businesses across Europe.

Many of the hauliers and car drivers caught up on the M20 and surrounding roads are foreign nationals. It’s not just the UK economy losing money. Firms across the continent must be feeling the pinch as the whole European supply chain is disrupted.

"So it is a surprise that not more EU member state governments aren't on the phone to the Elysee palace and asking President Hollande, 'what on earth is going on?'"

Migrants at the side of the road near the Channel Tunnel on Wednesday (Reuters)

11.42: French must deploy troops, says Nigel Farage

Nigel Farage, the Ukip leader who was himself caught up in the chaos at Calais yesterday, said he was "surprised" the French had not deployed troops in Calais to boost security. He told the BBC:

The intensity and the desperate efforts of those who want to get to Britain, and we understand why they do, is becoming more and more severe.

"Just talk to the lorry drivers who are having bricks thrown in front of their tyres, every attempt being made to actually stop the lorries so people can try and get on. The situation is bad.

"As far as we're concerned, do we need the Army in Dover? Actually the real problem is in Calais but the problem in Dover is because we put all our eggs in one basket, with all of our freight, nearly all of our holiday traffic, goes on that Dover-Calais route, we simply haven't got the border agency staff to check every car and check every vehicle."

11.36: 120 extra riot police for Calais

The French interior ministry is deploying an extra 120 riot police to Calais to deal with the ongoing crisis, The Telegraph's Rory Mulholland reports from the port town.

11.30: Eurotunnel delays continue - but UK passengers spared long queues

Judging by posts on Twitter, Eurotunnel passengers are not suffering major delays on the approach to the UK terminal in Folkestone - although services are still delayed by up to an hour as a result of cancellations caused by migrant activity overnight:

@LeShuttle Check in done. We arrived from Canterbury direction, M2.. And there was no traffic, no queues (except for trucks). #Eurotunnel — Anu Ylänen (@anupulu) July 29, 2015

@LeShuttle M2, A2, B2068 completely clear, no hold ups at all — Peter Empson (@PeterEmpson) July 29, 2015

@LeShuttle we got through on time on Wednesday morning. Not looking forward to going back Saturday night. — ROWLY 45 (@Rowly45) July 29, 2015

11.21: Hauliers demand France deploys military in Calais

France should deploy its military to secure the port of Calais, according to a trade association of British hauliers.

The Road Haulage Association (RHA) warned that the lives of lorry drivers are in danger because the French police lack the resources to deal with the crisis. Its chief executive Richard Burnett said:

It has become clear that the French authorities in Calais simply cannot cope. This has become an untenable situation and is obviously now beyond the capabilities of the French police.

"The RHA strongly repeats its request, made in June, for deployment of the French military to contain, segregate and control the migrant threat.

"We need to see help on a giant scale. We think it's a resources issue. The police resources are obviously limited and the military will have greater resources.

"For the thousands of British drivers whose lives are now being put at risk on a regular basis, a quick and effective solution to the current situation must be found.

"The news that yet another life has been lost in such tragic circumstances underlines the desperation of the Calais migrants."

Migrants gather on the side of the road as lorries queue to embark on shuttles at the Eurotunnel terminal on Wednesday (REUTERS/Pascal Rossignol)

11.08: Calais mayor calls from cross-Channel summit

Natacha Bouchart, mayor of Calais, has called for a summit involving ministers from France and Britain, Eurotunnel, the ports, and the municipality of Calais.

Speaking on radio station France Info this morning, she said: "It's simply a global hypocrisy that doesn't want to tackle the problems and the consequences of a decision of a European country that has different rules and which therefore must accept to change and to find acceptable solutions for all."

Ms Bouchart previously said Britain was "attracting" migrants as it had a "much more favourable" benefits system.

"You have a much more favourable regime in Britain than in other European countries," the mayor said. "The weekly benefits of £36 that are given to asylum seekers or migrants, which is a huge amount for people who have nothing in their lives," she told the Home Affairs Select Committee last October.

Mayor of Calais Natacha Bouchart (Matt Dunham/AP)

10.59: Operation Stack chaos 'simply unacceptable'

Back to Kent, where Operation Stack - in which lorries are parked on the M20 - is in force again today. The Federation of Small Businesses has written to the Government calling on ministers to address the travel chaos.

Stack began as a temporary measure in 1988, but it was now "simply unacceptable" that a workable solution has not been implemented in the intervening years, the FSB said. Its national chairman, John Allan, said:

On a local level, business meetings have been cancelled, deliveries are late and travel time from home and work is extended. And we have seen the ripple effect rapidly spreading across the country.

"Many small firms are spending valuable time and money trying to find viable alternatives to honour commitments to their customers, both at home and in continental Europe."

The Freight Transport Association last week said that Britain's haulage industry was losing £750,000 a day because of the problems lorry drivers have faced this summer trying to cross the Channel.

Operation Stack, in which lorries are queued on the M20, began in 1988 as a temporary measure

10.44: Home Secretary to convene Cobra crisis committee

Theresa May, the Home Secretary, is chairing an emergency Cobra meeting this morning to discuss with ministers the growing Calais migrant crisis. She was pictured leaving Downing Street at about 9.15am.

Cobra - named after its location in the Cabinet Office Briefing Rooms - is normally chaired by the Prime Minister, who is currently on a four-day tour of Asia.

Theresa May leaves Downing Street as she prepares to chair a Cobra committee meeting over the Calais crisis (Lee Thomas)

10.32: Leeds Castle blames crisis on loss of 10,000 visitors and £90,000 income

Officials at Leeds Castle, near Maidstone, blame Stack for a drop of up to 10,000 visitors in the past six to eight weeks, compared with the same period last year.

Spokeswoman Gemma Wright said: "Due to Operation Stack this year, we are approximately 30 per cent down on budgeted visitor figures which translates as roughly £90,000 income loss for the charity.

"We would like to praise the local authorities for all the hard work they are doing to try and ease the situation and find a solution. We just hope it comes soon."

Kevin Dryland, 55, who owns the Potten Farm shop in Sellindge, near Ashford, said the cross-Channel problems were having a devastating effect on small village businesses like his. He said:

It's having a massive impact. On Saturday, we had traffic queuing outside for three hours trying to get on to the motorway.

"The problem is with the constant closure of the M20, which then forces traffic to use the A20, which in turn causes gridlock in all the surrounding villages.

"All of the locals who us businesses rely on don't come out because of the gridlocked roads. We are a farm shop, so a lot of our produce ends up as waste."

10.19: Operation Stack costs economy £1.5m a day

Businesses large and small have united to call for a speedy resolution to the cross-Channel crisis - as shops struggle to receive supplies and welcome visitors.

Firms in parts of Kent are reporting huge falls in customers as Operation Stack causes queues of traffic to form outside their businesses.

Stack has led to sections of the M20 being turned into an HGV park for up to 5,000 lorries as freight traffic is forced to queue there whenever cross-Channel services at the Chunnel or Dover port are disrupted.

Kent County Council estimates the impact on the county's economy is around £1.5 million a day, and that there needs to be intervention from Government and Highways England.

Matthew Balfour, Kent County Council's Cabinet member for environment and transport, said:

"Operation Stack is a nightmare for the people of Kent who are unable to go about their daily business. Not only does it affect people's lives, but businesses are suffering and anyone trying to get to Dover for their summer holidays are stuck in miles of tailbacks.

"This is an urgent problem that needs to be dealt with by Government and Highways England."

Queues from Operation Stack on the M20

10.12: Migrants wait for darkness to break through fences

Migrants attempting to storm the Channel Tunnel in Calais are making the journey from their camps on foot, before waiting for darkness to break through fences.

Once the fences have been breached, they make their way onto the platforms and try to hide on lorries or freight trains, in order to make it into the UK undetected.

The picture was painted by Eurotunnel spokesman John Keefe:

They feel that have got a better chance of hiding in the dark or escaping undetected. Searching the trains can take a very long time, and this could mean significant delays being caused to freight services.

"It is freight services, not passenger services that are being affected. The two run on separate parts of the terminal. They position themselves around the terminal, on public land, and then when it becomes dark start to try and come through the fences.

"They go to the the platform area and the try to get into either trucks or trains directly, in that area and hope to get a ride into the UK. When they come through the fences we then send patrols to pick them up.

"They make their way to the platforms, the platforms are secured by large numbers of security personnel and police forces, and they are removed from that area and put on to buses by police. When there are hundreds, that simple process takes all night."

Migrants cross a bridge over the railway tracks of the Eurotunnel terminal on Tuesday night (AFP/ PHILIPPE HUGUEN)

10.01: 'None of 1,500 migrants reach UK'

Eurotunnel has confirmed that none of the 1,500 migrants who tried to storm the tunnel early today are known to have been successful in crossing the channel and were instead removed by French police.

It is a different story to early on Tuesday, when a large number were successful in crossing into Britain during the "migrant activity". They were stopped on the UK side and the authorities informed.

Eurotunnel also said that migrants are not getting "anywhere near" the tunnel itself, and that the disruption is being caused on the freight platforms.

09.45: Theresa May: We are working with French authorities

As Home Secretary Theresa May prepares to chair a meeting of the government's Cobra committee this morning, here's the latest video we have of her explaining how the British government is working closely with French authorities to tackle the migrant crisis:

09.38: How chaotic scenes unfolded at Calais early today

More details are starting to emerge of the chaotic scenes that unfolded in Calais early today.

A Eurotunnel spokesman was quoted by France 24 as saying all the company's security staff - about 200 people - were used to prevent the intrusions into the site, which largely took place between 12am and 6am.

Denis Gaudin, sub-prefect of Calais, told French newspaper La Voix du Nord: "The migrants are entering in little groups, finding holes all along the 22 kilometres (13.6 miles) of the boundary fence and heading towards the platforms."

09.30: Eurotunnel waits of up to an hour in Folkestone

Another travel update for people aiming to catch a Eurotunnel train from Folkestone: The firm says the wait on the UK side of the tunnel is now up to an hour, as a result of the overnight migrant activity, and it is running three services an hour.

"We can assure you that we're all working hard to resolve it," a spokesman said.

09.24: 'A human drama which is taking place every day'

Britain must shoulder some of the blame for the Calais crisis, a French politician has claimed, because the government "allows migrants to work without papers".

Xavier Bertrand, former minister for labour, employment and health and candidate for Nord-Pas-de-Calais-Picardie in regional elections this year, said:

In Calais, it's a human drama which is taking place every day. Only a naval blockade at the Libyan coast could provide a solution.

"The UK has responsibility in this matter too, England allows these migrants to work without papers. The English border must be at Dover and not Calais."

09.12: Calais migrant crisis: by numbers

Here's a handy explanation by numbers of what we know about the Calais migrant crisis:

09.03: Migrant activity now causing Eurotunnel delays

Another update from Eurotunnel, which says the migrant activity in Calais is now causing 30-minute delays at its Folkestone terminal:

Due to migrant activity overnight on our French Terminal, we're experiencing up to a 30 min wait on site from the UK. Apologies. ^SL — Eurotunnel LeShuttle (@LeShuttle) July 29, 2015

Operation Stack on the M20; we recommend that you check local traffic conditions on the Highways England website. ^SL — Eurotunnel LeShuttle (@LeShuttle) July 29, 2015

Our Passenger service is running with up to 3 departures per hour on both directions with a disrupted timetable. ^SL — Eurotunnel LeShuttle (@LeShuttle) July 29, 2015

08.59: Operation Stack back in force on M20 in Kent

More bad news for motorists in Kent: on top of the Operation Stack coast-bound closure of the M20 (see 07.56 post), the London-bound carriageway has now been shut between junctions nine and eight:

#OpStack: In addition to the #M20 J8-11 c/b closure, J9-8 Londonbound is being closed to allow extra space to queue freight traffic. #alert — Kent Police (UK) (@kent_police) July 29, 2015

08.53: Advice from Eurotunnel

While Eurotunnel has not reported any major delays from its Folkestone terminal this morning (although it is urging people to arrive an hour early), it has this advice for passengers from France:

Travelling from France, access to our Passenger terminal is congested by lorries. Don't queue up with trucks or use the Jct from Boulogne^SL — Eurotunnel LeShuttle (@LeShuttle) July 29, 2015

08.50: David Cameron adresses crisis from Singapore

In case you missed it earlier, Prime Minister David Cameron has addressed the Calais migrant crisis in Singapore while on a five-day trade tour of south-east Asia.

Speaking early today, he described the situation as “very concerning” and said Home Secretary Theresa May was working “very closely” with her French counterpart, including to fund new security fencing to protect the terminal at Calais and the entrance to the tunnel at Cocquelles.

Mr Cameron, who is travelling with journalists including The Telegraph's Matthew Holehouse, said:

We are doing everything we can. The Home Secretary will be chairing a ministerial COBRA meeting to make sure that everything that can be done working with the French is being done.

“I have every sympathy with holidaymakers who are finding access to Calais difficult because of the disturbances there. It is not a satisfactory situation. There is no point trying to point fingers of blame."

David Cameron speaking in Singapore during his four-day Asia tour (AP)

08.42: 'Biggest incursion effort in the past month-and-a-half'

For several weeks, there have been many attempts by migrants to enter the Eurotunnel premises in Calais, with the numbers growing significantly in recent days.

The attempts at storming the terminal on Tuesday night come after some 2,000 bids to enter the site were recorded the night before, in what was described as the "biggest incursion effort in the past month-and-a-half".

08.30: Migrant 'struck by truck leaving cross-Channel ferry'

French police sources now suggest the migrant who died last night - a man of Sudanese origin, believed to be aged between 25 and 30 - was hit by a truck that was leaving a cross-Channel ferry. Earlier reports said he had been hit by a truck as he tried to climb over a shuttle.

08.27: Latest pictures of migrants on tracks

Here are the latest overnight pictures from Calais, showing migrants desperate to reach Britain who managed to walk along railway tracks at the Eurotunnel terminal in the latest storming of the port.

08.18 MP: ' I can't believe we would allow this situation to occur in UK'

Damian Collins, Conservative MP for Folkestone, welcomed the new money pledged to tackle the Calais migrant problem - but critcised the French authorities for not enforcing their own restrictions. He said:

This investment is very welcome, it doesn't address the whole problem. It's partly an issue of enforcement from French authorities.

"They have allowed people willingly to break into the Channel Tunnel site. I can't believe they would be that lax in protecting an airport or another sensitive facility. But that has happened constantly throughout the summer. They have to enforce their own restrictions.

"This is happening within France. We have a role to play in supporting the situation and it is in our interests too. Not only is what's going on there tragic and involving a loss of life but it has terrible consequences for Kent.

"But principally, this is French territory. I can't believe we would allow this situation to occur within the United Kingdom - I can't remember an incident at the Channel Tunnel site in Folkestone where people, be they strikers or migrants, have broken into the site and entered secure areas.

"The French government needs to put more of its own resources into defending the tunnel and the port."

08.06 RAC: 'It's hard to see where this will end'

Operation Stack has been in force on the M20, on and off, for weeks - much to the dismay of motorists and locals in Kent alike.

A spokesman for the RAC Foundation said it was "hard to see where this will end".

Philip Gomm, head of external communications, said: "The TV pictures of queues in Kent might suggest this is a little local difficulty, but it has become a problem which is impacting the UK supply chain, and is affecting the travel decisions of people hundreds of miles away from south east England. Matters need to be treated with the urgency they deserve."

Trucks sit stationary on the side of the M20 on Tuesday as part of Operation Stack (Bloomberg)

07.56

Meanwhile, Kent Police has confirmed that Operation Stack - where HGVs are queued on sections of the motorway to avoid gridlock on the county's roads - remains in place on the M20 this morning.

The coast-bound carriageway is closed to non-freight traffic between junctions eight and 11. Tourist traffic for the Channel Tunnel can join the M20 at J11.

#OpStack is in place this morning from M20 J8-J11. J12 and J13 have reopened, but freight must still join the queue at M20 J8. #alert — Kent Police (UK) (@kent_police) July 29, 2015

07.45

Despite last night's migrant activity around the tunnel in Calais, Eurotunnel says NO delays are currently reported on its services.

However, it is this morning warning that timetables are disrupted and asking passengers to arrive around an hour before their departure time.

If you're travelling tonight visit our website for the latest Passenger service information here: http://t.co/l0KEhnM2W7 ^CM — Eurotunnel LeShuttle (@LeShuttle) July 28, 2015

07.41

According to French police, up to 1,000 migrants remain in the area around the Channel Tunnel.

A police source told the AFP news agency: "Everything happened overnight, and at 6am (5am BST), the police still have quite a lot of work to do," adding that "between 500 and 1,000 migrants" were still around the tunnel site.

07.34

According to French media, the migrant is the eighth person to be killed in the tunnel since the start of the month, and is believed to be a Sudanese national aged in his late 20s.

It is thought that he was hit by a truck as he tried to climb over a shuttle.

07.26

The death comes after 2,000 migrants tried to gain entry to Eurotunnel's French terminal on Monday night, causing chaos for cross-Channel travel.

A French spokeswoman for Eurotunnel said this morning: "I can confirm that one migrant died last night after 1,500 tried to storm the Eurotunnel."

07.20

BREAKING: One migrant died last night after at least 1,500 migrants desperate to reach Britain tried to storm the Channel Tunnel in Calais, operator Eurotunnel has said.

07.05

Yesterday, Theresa May announced an extra £7 million to protect the railhead, amid fears of misery for hundreds of thousands of families during the summer getaway.

Some 3,000 people, largely from Ethiopia, Sudan and Afghanistan, are camped in Calais in the hope of reaching Britain, according to an official count conducted at the beginning of July.

Benard Cazeneuve, the French interior minister, on Tuesday held talks with Mrs May on the issue.

It follows advice from the Foreign and Commonwealth Office to avoid Calais and use other routes due to industrial action by French farmers that had created long queues.

Problems have been compounded by strikes by French port workers, who have delayed the passage of lorries in Calais. It is costing the freight industry an estimated £750,000 a day.

One of Calais's migrant makeshift camps known as 'Jungle 2' (Rex)

06.55

Today's Cobra committee meeting comes after some 2,000 migrants broke through fencing at the Calais railhead in an attempt to reach shuttles carrying cars and lorries to Britain on Monday night.

A “number” were injured and fences were damaged as migrants attempted to reach the shuttles. It resulted in delays of an hour on the UK side and 30 minutes in France.

It was the biggest incursion in six weeks, Eurotunnel said, in a period in which eight people have been killed attempting to climb onto the shuttles that transport cars and lorries.

Lorries backed up on the M20 motorway amid Channel Tunnel chaos (Reuters)

06.45

Good morning and welcome to our live coverage of the ongoing migrant crisis in Calais.

Home Secretary Theresa May will chair a meeting of the government's Cobra emergency committee later today to address the chaos at Calais that risks ruining the summer getaway for British holidaymakers.

David Cameron said he has “every sympathy” with families who face long delays and diversions from Calais to other ports.

Speaking to the Telegraph's Matthew Holehouse in Singapore, he said Britain would co-operate with France and not “point fingers of blame” over responsibility for the crisis.

Stay with us throughout the day for all the latest updates.