Fresh food worth £2million is being thrown away each month because of illegal immigrants hiding in the back of lorries heading for Britain from Calais.

Entire truck-loads of imported fruit and vegetables have to be destroyed if stowaways are found inside the vehicle.

Freight bosses revealed that some £2million worth of produce has been written off each month since the start of the year amid fears of ‘contamination’ by foreigners who have broken into HGVs.

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Fresh food worth £2million is being thrown away each month because of illegal immigrants hiding in the back of lorries heading for Britain from Calais

Large quantities of fresh food destined for supermarkets and other retailers has had to be ‘condemned’ for this reason.

Home Secretary Theresa May agreed to an urgent meeting with the ‘increasingly worried’ food industry to try to find ways of better protecting imported produce from migrants.

Nigel Jenney, chief executive of the Fresh Produce Consortium, estimated that £10million of goods had been dumped by its members this year.

He said one-third of produce came from mainland Europe, mainly France and Spain, but problems had become so severe that some companies were now ‘doing their best to avoid Calais’.

He added: ‘The situation has got increasingly worse. Historically this would have been an exceptional incident. Now it is becoming much more prevalent.

‘In the last six months we estimate costs to the industry of products alone of £10 million. That’s fresh produce in the vehicle being lost.

Home Secretary Theresa May (pictured) agreed to an urgent meeting with the ‘increasingly worried’ food industry to try to find ways of better protecting imported produce from migrants

‘It is fresh produce, it’s for immediate consumption and not packaged in a way that makes the product totally sealed, and therefore if you have people in the back there is a risk of contamination.’

Many migrants clamber aboard lorries as they are being loaded – sometimes as far away as Spain – while others sneak aboard later in a journey.

But once an illegal immigrant is detected by the authorities, either at the port of Calais or in the UK, the cargo is deemed ‘contaminated’, no longer considered fit for human consumption and destroyed.

If this problem persists, it could lead to a shortage of supplies or a rise in food prices to cover the cost of ruined consignments.

The revelations came amid a growing clamour for action to tackle the immigration chaos at Calais.

The Freight Transport Association (FTA) had written to the mayor of Calais to call for her support for a campaign to address the worsening situation around migrant camps in northern France.

Entire truck-loads of imported fruit and vegetables have to be destroyed if stowaways are found inside the vehicle

More than 2,500 illegal migrants, many fleeing humanitarian disasters in Africa and the Middle East, are massing in shanty towns around the French city’s freight terminal in the hope they can smuggle on board UK-bound wagons.

The FTA wants to put pressure on the French and British governments — along with the European Union — to improve security and move groups of migrants away from the port.

Confrontations have been reported between migrants, police and hauliers as they make desperate attempts to board lorries. One lorry driver described the situation as being ‘like a war zone’.

Lorry drivers have been ordered not to stop within 130miles of Calais to try to minimise the risk of migrants clambering aboard in a desperate bid to reach Britain.

Haulage firms have told truckers that taking a break for a rest, to eat or refuel close to the port increases the prospect of stowaways sneaking on to their vehicles before they cross they Channel.

James Hookham, the FTA’s deputy chief executive, has written to officials in Calais and held talks with the Home Office amid claims the situation is now harming the British food supply chain.

He said: ‘We are pressing for more visible commitment from the French government to [tackle] criminal activities on French soil and [face] their responsibilities for the protection of British drivers while in their jurisdiction.

‘We have some lorries being surrounded by dozens, if not hundreds, of people, trying locks, attempting to get into containers, stowing themselves underneath or even slitting open curtain-sided vehicles to get in. It’s chaos.’

Once lorries have reached the country, the UK Border Force uses an array of search techniques including sniffer dogs, carbon dioxide detectors, heartbeat monitors, scanners and visual searches to find stowaways.

Britain has pledged £12million to help the French tighten security at the terminal. Much of the money is being spent on moving the 9ft-high fences which guarded world leaders at the recent Nato summit to Calais.

Large quantities of fresh food destined for supermarkets and other retailers has had to be ‘condemned’ for this reason

Calais’s mayor Natacha Bouchart has said migrants were desperate to reach Britain to claim benefits, because they believed it was like El Dorado, the mythical lost city of gold.

But the UK Chamber of Shipping told MPs that stowaways found on Dover-bound ferries pleaded to be sent back to France, because they did not want to get caught up in the asylum system in the UK.

Instead, they wanted to have another go at sneaking into the UK ‘out of sight’ of the authorities so they could work illegally in the black economy. Under British rules, asylum seekers are barred from working.

Earlier this month it was revealed that police in northern France have stopped migrants attempting to sneak into the UK 18,000 times this year – but they admit not knowing how many have evaded their controls.

Immigration ministers James Brokenshire said: ‘Law and order in and around Calais is the responsibility of the French authorities but the UK continues to liaise closely with them.