The home secretary has been criticised after admitting that more than 1,000 foreign prisoners who could have faced deportation upon their release from jail have been freed without any further action.
Charles Clarke said in a written statement to MPs on Tuesday that 1,023 such prisoners had been allowed to go free in Britain at the end of their sentence between February 1999 and March of this year.
The Conservatives said the cabinet minister should now appear before MPs to explain the failures.
Offenders who were released without being considered for deportation included three murderers and nine rapists, the Home Office said. Five had been convicted of committing sex offences on children.
The home secretary said it would be difficult to recapture all the offenders due to the large number involved.
"I can't say hand on heart that we will identify where each one of those is, but we are working on that very energetically," Clarke said.
So far, the Immigration and Nationality Directorate (IND) has tracked down 107 of the total, leading to 20 deportations.
The embarrassing error, which only came to light after the Commons public accounts committee raised questions last October, was caused by the Prison Service not focusing on the nationality of its prisoners, Clarke said.
And the IND was preoccupied with other matters, he explained.
"We simply didn't make the proper arrangements for identifying and considering removal in line with the growth of numbers that were there," admitted the home secretary.
"That is a failure of the Home Office and its agencies for which I take responsibility.
"Both the Prison Service and the IND failed to carry out their responsibilities in the way they ought to have done."
But he added that "they have both taken steps to lead me to be confident that it is now being done properly".
Shadow home secretary David Davis said the news was "astonishing" and "the latest in a long line of failures which have jeopardised the protection of the public".
He said that 160 of the offenders were recommended for deportation as part of their sentencing but only five have been deported.
"This serial incompetence beggars belief," said Davis.
"How many more times must we put up with the Home Office's abject failure to protect the public, and how many more times will they seek to duck responsibility for the issue?
"This matter should have properly been a matter for scrutiny by the House of Commons.
"Instead the home secretary chose to brief the press then issue a written statement.
"The home secretary urgently needs to come to the House of Commons to explain the situation."
