TONY BLAIR will make a final, passionate appeal to his MPs today to agree to powers, sought by the police, to hold terrorist suspects for up to 90 days without charge.

At his monthly press conference he will insist that there is a “compelling case” for such an extension, despite a previous government offer to compromise on a lower figure.

The Prime Minister’s aides stamped on weekend claims that Downing Street signalled he was ready to back down, as a series of ministers used interviews to make the case for a maximum 90-day period of detention before suspects are charged or released.

Mr Blair will make a similar argument tonight at a meeting of the Parliamentary Labour Party, a Downing Street source said. He was boosted by a Sky News/YouGov poll which found that 72 per cent of people questioned backed extending the limit from its current 14 days to 90, a third of them regardless of judicial oversight, with only 22 per cent opposed to 90 days.

None the less, the Prime Minister’s wish for the full 90 days would face almost certain defeat in the Commons, making concessions inevitable before the votes on Wednesday when the Terrorism Bill returns for its report stage.

Lord Falconer of Thoroton, the Lord Chancellor, admitted that Mr Blair would have to back down, saying: “There is an issue about whether it can get through the House of Commons. If it can’t, there will need to be a compromise.”

Mr Blair’s tough stance appears to be intended to strengthen the hand of Charles Clarke, the Home Secretary, in negotiations with opposition parties today and to enable Mr Blair to blame his opponents, especially the Tories, if he fails to get his way. A Labour source pointed out that the Conservatives were in direct opposition to the police over the issue.

Labour MPs, however, attacked Mr Blair’s intervention as a breach of an undertaking by Mr Clarke last week to seek a compromise on a lower figure. Frank Dobson, the former Health Secretary, said that the debate had become a question of trust and that Labour MPs had to be able to rely on the word of the Home Secretary and Labour whips speaking on behalf of the Government.

David Davis, the Shadow Home Secretary, has faced dissent from some Conservative MPs, but said that the Commons would not accept an extension of detention without charge for more than 28 days.

Mr Clarke, meanwhile, has ruled out setting up a fund to compensate victims of terrorist attacks, arguing that they should not receive special treatment. He said: “Whether you are stabbed outside the pub or maimed by an explosion on a Tube train, it’s not actually the way in which you are injured that is the key thing — provided it’s a criminal act — but the extent of the injuries.”

In an interview with The Daily Telegraph Mr Clarke said that he is alarmed by the daily briefings he receives from the security services. He said that terrorist cells were operating in Britain and that more than one attack had been thwarted since July 7.

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