Gordon Brown backed calls for police to be given up to 90 days to question al- Qa'ida suspects without charge as he vowed to take personal charge of the fight against terrorism if he becomes prime minister.
The Chancellor - supported by John Prescott, the Deputy Prime Minister - put proposals to extend the detention period back on the political agenda a year after the 90-day plan was thrown out by MPs.
A raft of Home Office Bills in the Queen's Speech on Wednesday will place the battle against terrorism, organised crime and illegal immigration at the heart of the Government's programme over the next year.
The speech will also set out plans to toughen action on antisocial behaviour by fining the parents of persistent troublemakers.
The controversy over questioning terrorist suspects was reopened by Sir Ian Blair, the Metropolitan Police Commissioner, who said he believed an extension from the current 28-day period would have to be "examined again in the near future".
Mr Brown said: "I completely agree with him. Given the scale of the threat we face, we must give the security service and police not just the resources they need but the powers they need to gather securely the evidence and use that evidence to gain convictions."
The Chancellor declared that safeguarding Britain against terrorism would be his "first priority". He told the Sunday Times: "If you are prime minister, you cannot devolve responsibility for protecting the nation."
Mr Brown's intervention is likely to irritate John Reid, the Home Secretary, who has been championed by some Blairite MPs as a rival to the Chancellor to succeed Tony Blair.
Mr Reid fuelled speculation yesterday that he may stand for the leadership with an attack on David Cameron, insisting there was a clear "dividing line" between himself and the Tory leader over the treatment of young offenders.
Some senior police officers argue that the case for an extension has been made stronger by the detection of an alleged plot to blow up transatlantic airliners and MI5's warning last week that Britain faces more than 30 active terrorist plots.
Mr Prescott told BBC1's Politics Show: "We got 28 days, it's still felt by the police perhaps not to be adequate and if that's the case, parliament could certainly revisit and consider it."
But Dominic Grieve, the shadow Attorney General, called for detailed explanations as to why the limit should be changed.
He told BBC Radio 4: "If there is credible evidence that an extension is needed, we will consider that pragmatically."
A report published today by the Joseph Rowntree Reform Trust accuses the Government of allowing "electoral motives" to undermine the fight against terrorism and claims that ministers are "trying to win over the white- working class vote".Reuse content