Britain is to send a two-mile long fence to France to stop illegal migrants boarding Channel Tunnel trains.

Security around the train line at Coquelles and the ferry port of Calais is being stepped up after a dramatic escalation in the number of people trying to sneak into Britain.

Home Secretary Theresa May said she wanted to send a 'very clear message' that people will not be able to get through to the UK but ruled out searching all vehicles once they arrive on British soil.

Britain is to send a two-mile long fence to France to stop illegal migrants boarding Channel Tunnel trains at Coquelles (pictured)

Migrants have been seen trying to hide in vehicles waiting to board Channel Tunnel services at Coquelles and at the ferry port of Calais.

Up to 3,000 people are now living in a makeshift camp at Calais while attempting to find a way to reach Britain.

Ministers will hold urgent talks with hauliers this week to see what more can be done to tackle the problem.

The UK is to send two miles of high-security fencing to cover both sides of the platform at Coquelles to offer greater protection to lorries and cars which are crossing the Channel.

The Foreign Office has warned travellers to lock their doors in slow moving traffic and secure vehicles when left unattended.

In a sign of the scale of the challenge the authorities face, last year the Border Force stopped 39,000 people from trying to enter Britain illegally, twice the figure seen in 2013.

Mrs May said efforts were being stepped up 'to ensure that people aren't able to get into the lorries in the first place'.

She added: 'We are working very closely with the French authorities on this issue. We have been doing a number of things to increase security around the port.

'We are making a number of changes at Calais to increase security, we're also going to be putting some extra security fencing at Coquelle at the entrance to the Tunnel.'

Migrants have been seen trying to hide in vehicles waiting to board Channel Tunnel services at Coquelle and at the ferry port of Calais

Ten-year-old Aman Facih, from Eritrea, is bundled into a gap in a lorry by his brother Daniel amid chaos at Calais

Work will begin on erecting the fence tomorrow, but is unlikely to be finished until the end of July.

It will seek to increase security around a 2.5-mile section of track and platforms used by the trains which carry lorries back to Britain.

It follows the reports that an Eritrean migrant was killed on the French side of the Channel Tunnel after trying to board a moving freight train at Coquelles last week.

Mrs May was pressed by BBC One's Andrew Marr about why all vehicles were not searched when they also arrived in Britain, but she stressed that the focus of security was on the French side of the Channel.

'The vehicles going through at Calais and Coquelle are searched by French authorities, there will be vehicles searched by UK authorities too. 'We are looking to enhance our capability of doing that. We have enhanced our capabilities here in the UK at UK ports too.

'But in terms of the Mediterranean migration that is leading people up to Calais what we also need to do is to break the link between making this journey and thinking this is going to lead to being able to settle in Europe.

'We need to send a very clear message that people will not be able to get through to the UK.'

Home Secretary Theresa May said she wanted to send a 'very clear message' that people will not be able to get through to the UK but ruled out searching all vehicles once they arrive on British soil

Immigration minister James Brokenshire will hold talks with the Road Haulage Association this week, amid warnings of the catastrophic effect of cargo having to be destroyed if stowaways are found in lorries.

He told the Sunday Telegraph: 'I am very concerned to hear some of the stories of the impact of what we have seen on those who are trying to do their jobs and get produce and trade into the UK.

'It is extremely hard and extremely unsettling and I can only imagine the concern this causes to individual lorry drivers.'

'I want to see people go off on their holidays, get away for those breaks and strengthening the links between those Channel ports,' he added.

Aid workers have reported a 'catastrophic' situation, with predictions that some 2,000 more migrants displaced from war-torn countries including Eritrea, Syria and Afghanistan could arrive over the summer.