The troubled UK Border Agency faces a backlog of more than 200,000 cases - the equivalent to the population of Newcastle - MPs have warned.
Missing foreign criminals, failed asylum seekers, illegal immigrants and others refusing to leave the country make up more than 275,000 cases, which the agency still needs to deal with, the Commons Home Affairs Select Committee said.
Keith Vaz, the committee's chairman, said the backlog, which will take years to clear, was unacceptable, adding that the agency seems to have "acquired its own Bermuda triangle".
The latest damning report on the UK Border Agency's work has also said the Home Affairs committee did not believe the Government's aim of cutting the 260,000 student visas issued each year by a quarter would benefit the UK.
Students should be excluded from the net migration figures instead, it said.
Britain would then continue to attract international students, a market worth £7.9 billion, and still be able to aim to meet David Cameron's pledge to cut net migration from 250,000 to the tens of thousands by 2015, the report said.
The Home Affairs committee report said the UK Border Agency backlog of more than 275,000 included:
- At least 150,000 migrants who have been refused permission to stay in the UK
- 21,000 asylum cases
- 3,900 foreign offenders living in the community
- A further 57 foreign criminals who were released in 2006 without being considered for deportation have not yet been traced
And the so-called 'controlled archive', used for cases where the agency has lost track of the applicant, contains 80,000 asylum applications and 21,500 immigration cases, the report said.