Downing Street yesterday ruled out offering an amnesty for illegal immigrants and failed asylum-seekers still in Britain.
The move has previously been supported by Boris Johnson, the Mayor of London. But Prime Minister David Cameron's spokesman said: "That is not something we are considering."
His comments came after it emerged that the UK Border Agency is working its way through a backlog of more than 275,000 cases – equivalent to the population of Newcastle.
Keith Vaz, the chairman of the Home Affairs Select Committee, said the agency had "acquired its own Bermuda triangle". The anti-immigration campaign group Migration Watch UK released a report claiming 60,000 bogus students could have entered Britain last year.