Damian Green, the UK immigration minister, has stated that the government is powerless to close the loophole in the rail system that s allowing passengers to enter Britain without undergoing border checks.
Dubbed the 'Lille loophole', the problem concerns that fact that passengers are able to board a Eurostar train in Brussels with a ticket to Lille, but then remain on the rain until they reach London without going through any border checks.
France and Belgium are both members of the Schengen agreement, which permits people to cross borders between the member countries without undergoing passport checks.
Despite the fact that the UK opted not to be a part of this agreement, Mr Green has stated that the British government is powerless to close the loophole without the support of the European countries.
Speaking to BBC Radio 4's The Report, he said: “There are strict British immigration controls in place in France and Belgium and we have UK Border Agency officers based at St Pancras to target those we believe are intent on entering Britain illegally.
“We are currently working closely with our Belgian counterparts and Eurostar to resolve this as quickly as possible.”
According to the radio programme, UK border staff, who have previously attempted to check the status of travellers, have been threatened with arrest. One was reportedly told by Belgian police: “This has got to stop, you are not in Britain now, you are in Schengen. If they make a complaint, you will be arrested.”
The news follows accusations that the Home Office could have let an unknown number of illegal immigrants into the UK after relaxing border checks over the course of the summer in a bid to reduce queueing times at airports.