Migrants in France are forcing their way onto Britain-bound trucks, often damaging the vehicles and forcing haulers to dump millions of dollars worth of contaminated food.

Europe is facing an escalating migrant crisis as conflicts in the Middle East and Africa spur the numbers seeking asylum in the region.

In the port of Calais, which is also the French entrance for the Channel tunnel between England and France, migrants regularly try and hide in vehicles to travel into Britain.

The problem intensified on Tuesday as streams of migrants tried to board trucks that were forced to a halt after a strike against the cross-Channel ferry caused traffic chaos on both sides of the channel.

The U.K.'s Freight Transport Association spokesperson Claire Britcher said drivers sitting in gridlock for hours were "sitting targets" for migrants who slashed open soft-sided trucks and broke locks in an effort to get inside.

The FTA, which has 14,000 members, said £2 million ($3.1 million) in food is written-off each month on the cross-Channel route due to contamination risks over fears that the food was damaged or made unfit for consumption by people climbing on board.

Another U.K. trade group, the Fresh Produce Consortium, estimate that £10 million ($15.7 million) has been lost in spoiled fruit and vegetables and insurance bills for incidents involving migrant stowaways in Europe this year.

Many drivers are responsible for their own trucks and damage to vehicles can put them out of action, plus they have to handle repair costs. One driver in Calais told CNN the situation is getting worse every day as migrants look for any way to sneak on board: stowing inside the load, lying on the top of the truck, and even holding onto the undercarriage.

There are believed to be around 3,000 migrants based in a camp in Calais. Britcher said drivers heading to the French port, which carries £89 billion ($140 billion) of trade each year, are increasingly worried about their safety.

"It's an incredibly dangerous situation," she said. "Lots of these migrants are armed and threaten the drivers. This is what they face every time they enter the port."

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- CNN's Florence Davey-Attlee in Calais contributed to this report.