Home Secretary Charles Clarke was under monumental pressure to resign over the foreign prisoner scandal last night - and to prove what he knew and when.

It emerged that police were only handed the first names from a list of 900 freed prisoners on Tuesday, even though Ministers were first warned about the bungle ten months ago.

Tony Blair was challenged to disclose what he knew of the hugely damaging gaffe, as the spotlight focused on the 288 prisoners who were released since alarm bells were first sounded in July.

The Prime Minister insisted he did not know details of the 288 until yesterday.

Conservative leader David Cameron called for Mr Clarke's scalp in a highly-charged exchange at Prime Minister's Question Time.

The Home Secretary has confirmed he offered his resignation at 4pm on Tuesday after the scandal emerged publicly for the first time, but it was declined by Mr Blair.

The Association of Chief Police Officers revealed it had began processing names provided by the Home Office in a bid to track down 916 outstanding offenders.

Initial results have already been returned to the Home Office after checks on the Police National Computer, it was confirmed. However, a Home Office spokeswoman said no further details were being revealed at this stage.

In further confusion, Mr Blair's official spokesman i nsisted Ministers only became aware in February that foreign prisoners were still being freed.

The massive blunder saw 1,023 overseas criminals released from jail without being considered for deportation, including murderers, rapists and paedophiles.

In the Commons, Mr Cameron said Mr Clarke was unable to give proper leader-ship to his department and accused him of misleading the public.

"We now know even after Ministers were told about the problem in July, 288 prisoners were released without being considered for deportation," he said.

"Why did the Home Secretary last night describe that as 'very, very few people'?

"This Home Secretary has presided over systemic failure.

"He's failed to deal with it and last night he misled the public about the scale of the problem."

Mr Blair said: "I did not know the details of the figures the Home Secretary gave until today.

"However, it is as a result of the Home Office putting out the figures that we actually know them. It is therefore quite wrong that these figures were somehow concealed by the Home Secretary.

Mr Blair added that "over 70" of the 288 released between August last year and the end of last month had now had their cases considered, and "some of them have been deported".

There were jeers from the opposition benches as Mr Blair said: "The reason we can give the figures is because there is a proper case management system in place."

He stressed that an investment of #2.7 million in the Immigration and Nationality Directorate meant that all foreign prisoners' cases were being considered for deportation before release for the first time "in decades".

Shadow home secretary David Davis repeated calls for Mr Clarke to resign, saying: "I can't think of a stronger demonstration of a Minister not in charge of his department. This is yet another example of his department's failure and incompetence."