LONDON (AFP) -- The furor in Britain over the release of foreign prisoners without deportation escalated Friday when Prime Minister Tony Blair's embattled government revealed that five of the convicts had gone on to become repeat serious offenders.

Home Secretary Charles Clarke, facing calls to fall on his sword and resign for failing to safeguard the public, said the five had been convicted of violent disorder, grievous and actual bodily harm, and drug crimes.

A "thorough search" of judicial and penal records had taken place, Clarke said, but it yielded no cases in which offenders had been convicted of the most worst crimes such as murder, and other offenses.

"I very much regret the shortcomings which I have reported," he said.

"The genuine shortcomings which have been revealed in dealing with foreign national prisoners will be repaired and we will learn the lessons to make whatever further changes are needed to improve the quality of what we do across the whole Home Office," the ministry in charge of law and order in Britain.

When pressed by journalists later, Home Office officials revealed that two foreign prisoners have been accused of rape since they were wrongly released by the Home Office.

One case is still being investigated by police and the other has been dropped because of lack of evidence.

Clarke touched off a furor on Wednesday when he acknowledged that 1,023 convicts of foreign nationality had not been considered for deportation -- as they should have been -- upon their release.