Gordon Brown's plans to double the 28-day limit on the detention of terrorist suspects were in crisis yesterday after the country's chief prosecutor cast doubt over the need for any increase.
Doubts are rising over whether the Prime Minister will be able to win Commons backing for the extension after the controversial proposal suffered a fresh succession of body blows.
Sir Ken Macdonald, the Director of Public Prosecutions, told the Commons Home Affairs Select Committee he was satisfied with the maximum time for questioning suspects before they are charged.
The former attorney general Lord Goldsmith said he opposed increasing the limit to 56 days and Jonathan Evans, the head of MI5, also refused to support the move.
The committee now looks certain controversially to oppose Mr Brown's plans. That would give confidence to Labour MPs who oppose the increase, leaving him with a daunting struggle to force it through Parliament.
Sir Ken told the MPs that the Crown Prosecution Service had found the 28-day limit, which it asked for two years ago, to have been useful and effective. He said: "Our experience is that we have managed and managed reasonably comfortably."
He said he had not requested a further extension this time and disclosed he had not even discussed the subject with the Prime Minister or Jacqui Smith, the Home Secretary. Sir Ken said he respected the arguments for a greater time limit, but added that 28 days "has suited us quite nicely".
He also warned there would be a problem in persuading judges to grant an extension beyond 28 days as prosecutors would find it hard to argue there was a chance of unearthing fresh evidence.
Lord Goldsmith, who left the Government in the summer, told MPs: "I am sure the reasons for making proposals are based on a genuine belief it is the right thing to do in protecting the country. I do not take the view that, if the proposal was to extend to 56 days, that that is justified by the evidence."
He disclosed that he had opposed Tony Blair's unsuccessful attempt two years ago to raise the limit from 14 days to 90 days – and would have resigned from the Government if it had been forced into law. He said: "If the 90-day proposal had come from the Commons unamended, I would have found it impossible to vote for it in the Lords."
Earlier, the committee travelled to MI5 headquarters for a private briefing on the terrorist threat facing Britain. Mr Evans refused to support the Government's planned extension, telling the MPs it was not a matter for him. One security source said: "This is up to the police and the DPP. We just provide the intelligence – it is up to them what they do with it. There may be some cases where it would be helpful, but no one should think it's a magic wand."
Mr Evans also told the MPs that MI5 backed the principle of using phone-tap evidence from investigations as long as the methods could be protected.
Ms Smith, Sir Ian Blair, the Commissioner of the Metropolitan Police, and Lord Carlile of Berriew, the independent regulator of terrorism legislation, are the only witnesses to the committee to have backed the extension. One committee source said: "It's not exactly an overwhelming case."
Shami Chakrabarti, the director of the human rights group Liberty, said:" If neither [Sir Ken and Lord Goldsmith] is persuaded of the case for extension, why should members of parliament take a leap of faith?"
David Davis, the shadow Home Secretary, said: "Terrorism will be defeated by good intelligence, professional policing and the rigorous application of British justice, not by unnecessary incursions into the freedoms and rights British subjects have had for centuries."
The Prime Minister's spokesman said: "It is the Government's view there is a case for considering an extension beyond 28 days as long as there are appropriate judicial and parliamentary safeguards in place."
For and against extending the 28-day limit
Sir Ken Macdonald, Director of Public Prosecutions
Lord Goldsmith, Former Attorney General
David Davis, Shadow Home Secretary
Nick Clegg, Liberal Democrat home affairs spokesman.
Shami Chakrabarti, Director of Liberty.
Eric Metcalfe, Director of human rights policy, Justice
Rachel North, Survivor of July 7 bombing
Mohammed Abulkahar and Abul Koyair, Wrongly arrested in Forest Gate raids
Gordon Brown, Prime Minister
Jacqui Smith, Home Secretary
Sir Ian Blair, Metropolitan Police Commissioner
Lord Carlile of Berriew, QC, Government's independent reviewer of terrorism legislation
Jonathan Evans, Director of MI5Reuse content