As many as 500 "undesirable" European nationals may have been allowed into Britain as a result of a government pilot scheme to reduce passport checks at Britain's airports over the summer, Labour claimed yesterday.
In a disclosure that will put further pressure on the Home Secretary, Theresa May, research by the party found that in the same period in 2010 there were 564 European nationals, including criminals and people previously refused entry, turned away as a result of checks by border staff.
Chris Bryant, the Shadow Immigration Minister, said: "If over 500 European nationals, who under the Home Secretary's pilot ceased to be routinely checked through biometrics, were stopped at the border last summer, how many came through the border this summer?"
Tomorrow the Home Affairs Committee will question Brodie Clark, the former head of the UK Border Force, who resigned after an acrimonious dispute with Ms May during which she accused him of ignoring ministerial orders not to relax border checks on non-EU entrants.
But Mr Clark is expected to tell the committee he acted to relax border controls further than authorised by Ms May only because he was required to by the police to prevent overcrowding.
He will say that a three-year-old directive obliged him to act if police decided the situation was a threat to public order.
It also emerged yesterday that coach passengers arriving in Britain via Dover were not properly checked by border staff for four years.
A relaxation quietly introduced under the last Labour administration to ease queues at the port of Dover in 2007 was only halted 10 days ago when senior border officials were suspended following the latest case.