The backlog in the asylum system doubled last year and is growing, an official report has revealed.
The number of asylum cases which were not dealt with increased to 8,700 in the second quarter of 2008 compared with 4,200 a year earlier, the National Audit Office said.
Even after their asylum claim is rejected, fewer than one in 10 asylum seekers processed under a new system are removed from the country.
Removing one family can cost the taxpayer up to £60,000, the report found.
The auditors also said the Home Office was on course to miss its target to clear the 450,000 "legacy" cases discovered four years ago and which cost the taxpayer £600 million last year.
And there were no measures to track those granted asylum so they could be returned home when their right to stay expired, they said.
Tory MP Edward Leigh, chairman of the Public Accounts Committee, said the UK Border Agency (UKBA) was "struggling to cope" with asylum cases.
The damning report revealed the overall backlog grew despite a fall in the number of asylum applications in the last five years from 84,000 in 2002 to 23,000 in 2007.
The UKBA had an "improved grip" on the asylum process since its last report, the NAO said, but its new system for processing asylum applicants had not led to an increase in asylum removals.
Mr Leigh added: "If things go on as they are, this backlog will become a lot bigger."