Hauliers travelling to the UK are under increasing pressure as the number of fines issued to drivers for carrying migrants has more than tripled over the last three years to 3,319 in 2014/15. The figures, released thanks to a Freedom of Information (FoI) request from the Press Association, come as the crisis in Calais continues to disrupt lorry drivers and tourists travelling to and from the continent.

Hauliers face an on-the-spot fine of up to £2,000 ($3,116) per stowaway if they are found in their trailers. The data revealed that there were 998 fines issued in 2012/13, and over the past three years 6,494 migrants have been found on or in the vehicles.

"It is in all of our interests to combat attempts to enter the UK illegally, which can damage the haulage industry financially and place the safety of drivers at risk. That's why we recently announced the introduction of a new secure zone at Calais for UK-bound lorries, providing a secure waiting area for 230 vehicles," a Home Office spokesperson said.

"Most hauliers take their responsibility for vehicle security seriously but, despite co-operation from the British haulage industry, Border Force estimates one third of lorries arriving at the UK border do not have basic standards of security.

"The purpose of the civil penalty regime is to ensure that all drivers are taking reasonable steps to stop migrants from boarding their lorries. Drivers who can show they have taken simple steps to secure their vehicles will not receive a penalty."

The Calais crisis has become a hot political issue after 1,500 migrants attempted to access the UK through the Eurotunnel. A young Somalian man died in his attempt to reach Dover, and others have since seriously injured themselves in their attempts to get to Britain. The UK government has promised to give the French authorities £7m to help bolster security around ports and docks. David Cameron mostly recently pledged more sniffer dogs and fencing in a bid to avoid disruptions and keep lorry drivers safe.

But, with Cameron now on holiday, the Conservative administration has come under further pressure to do more about the situation. Tim Farron, the Liberal Democrat leader, visited Calais yesterday (5 August) to assess the situation for himself and criticised the prime minister for referring to the migrants as a "swarm". Elsewhere, Ukip have called on the government to draft in the Army to the British Border Force as it attempts to process some of the migrants.

The Road Hauliers Association, which represents UK logistics operators, had not responded to a request for comment at the time of publication.