Thirty-eight offenders who were convicted of crimes including manslaughter, rape and child abuse have not been located. A further 11 foreigners convicted of serious offences but not considered for deportation have also not been found, it is understood.

Charles Clarke has had to admit to MPs that at least half remained at large.

In a further blow to the Government, the Home Office admitted last night that an Iraqi Kurd wanted for attempted murder and rape was allowed to stay in Britain despite a judge’s recommendation that he be considered for deportation.

Caliph Ali Asmar, 25, a failed asylum-seeker, is a prime suspect in the attempted murder at Easter of a Latvian man who was stabbed twice in the shoulder and chest.

Police also want to question the Kurd over a serious sexual assault at an address in Hull just a year after he was freed from prison in March 2005.

The latest disclosures came as Mr Clarke tried to rescue his career. He told the Commons that 32 of the 79 most serious offenders had been tracked down and that officials had ruled out deporting another nine.

A Home Office spokeswoman confirmed that the remaining 38 had left the addresses provided to police. A further 11 serious offenders have been identified but the Home Office would not say if any had been found.

It also refused to say how many of more than 800 foreigners convicted of less serious offences had been tracked down.

Nor, despite Mr Clarke telling MPs that deportation proceedings had begun in hundreds of cases, would the Home Office say if the number actually leaving the country had risen above the figure of 20 announced last week.

In the House, Mr Clarke announced a series of measures designed to convince the public that he and the Government have a grip on tackling the deportation of foreign national prisoners.

Tony Blair said that the new plans amounted to “automatic deportation” of foreign national prisoners, but that statement was immediately attacked by Michael Howard, who said that under the Human Rights Act there had to be a process of consideration and appeal.

Mr Clarke was more cautious, insisting that there would only be a presumption that all such prisoners would be deported.

The Home Secretary admitted that the disaster had been “an unedifying spectacle for all of us in the Home Office who are charged with the protection of the public. But I said I wouldstay and put the situation right.”

Mr Blair went out of his way to back Mr Clarke, who has presided over the worst blunder concerning the penal system since Labour came to power.

The Home Secretary bought time in his fight to stay in his job after receiving strong backing from the Prime Minister. But Mr Clarke remains at the mercy of events and could still be forced out if there are serious cases of reoffending by foreign prisoners still at large.

However, by announcing a radical overhaul of the deportation system intended to ensure that virtually all serious foreign criminals are deported, Mr Blair and Mr Clarke were clearly trying to turn the spotlight away from past failure to a future get-tough policy.

Downing Street, describing the move as the biggest changes for a decade, said the aim was to rebalance the system in favour of the people and not those who had been convicted. It would be presumed that serious criminals would be deported. “That is the new default setting,” Mr Blair’s spokesman said.

The only exceptions would be cases where deportation could not happen for “operational reasons” or because someone’s life was in genuine danger.

Government sources said the change would mean that most of the 2,500 people who had not been deported for various reasons over the past two years would be kicked out in future. That would mean fighting cases brought under the European Convention on Human Rights in the courts and bringing in laws to override it if necessary.

Mr Blair, anxious to limit changes in his imminent reshuffle, has succeeded in his initial aim of avoiding any departures from the Cabinet before today’s elections.

He wants Mr Clarke to stay where he is but he has the option of moving rather than dismissing him.

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