Gordon Brown faces his biggest political battle since taking over as Prime Minister after opposition parties pledged to defeat a renewed bid to extend the time that suspected terrorists can be detained without charge from 28 to 42 days.

Jacqui Smith, the Home Secretary, today announced the Government's latest proposals to break the political deadlock, claiming that police required the option of having more time to question terror suspects when there was a "compelling operational need".

In a fresh attempt to win over opponents, the Home Secretary added that she would only have the power to extend the questioning time on an investigation-by-investigation basis, and for a 30-day period, if police specifically requested it during major anti-terror inquiries.

She added that every such extension granted would then be put before MPs for approval within 30 days of the decision, introducing an unprecedented element of parliamentary control over and debate about the conduct of fast-moving security operations.

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• Pictures: Glasgow airport attack

BACKGROUND

• Brown plans to double 28-day detention limit

• Men in bungled raid say police attacked again

• More than Vigilance

• 'Dirty bomb' mastermind plotted wave of atrocities across Britain

• Jihadi house parties of hate

Related Links

• Q&A: 42-day pre-charge detention limit

• 'Lyrical terrorist' given suspended sentence

• Law chiefs question longer terror detention

However, Mr Brown faces a huge battle to win over opposition parties and his own backbenchers over the plans.

The current limit of 28 days was itself a compromise after a failed attempt to increase the maximum detention limit to 90 days led to Tony Blair’s first ever defeat in the Commons in November 2005. Today, Conservatives and Liberal Democrats have already pledged to oppose them when they are put before MPs.

Releasing her proposals today, Ms Smith said: "All of us can agree that, if a higher limit than 28 days is needed because of exceptional operational reasons, then such powers must not be used rashly or routinely.

"The purpose of this paper is therefore to set out the case for making it possible to go beyond 28 days, but only where this is exceptionally required and then only for a strictly limited period of time.

"Such powers should only be used where there is a clear operational need related to a particular operation or investigation and should be supported by strong parliamentary and judicial safeguards.

"I believe this approach is significantly different from the one originally proposed by Government and that it balances the need to protect the public by extending the limit when and where there is a compelling operational need against any risk of introducing blanket powers."

The Conservatives, Liberal Democrats and civil liberties groups, however, responded saying that there was no evidence that any extension was needed, and accusing ministers of abandoning attempts to seek consensus on the issue.

Central to the Tories' case is that the Government already has the power necessary to deal with terrorist suspects, and does not need further legislation. Under the Civil Contingencies Act, supported by the Conservatives, the Home Secretary already has emergency powers -allowing suspects to be held for a 30-day period above the current 28 days.

David Davis, the Shadow Home Secretary, said: “When the Government start bamboozling like this, you know the game is up.

“They are making a proposal for something they still have not proved necessary. They have lost the argument to further extend pre-charge detention beyond 28 days again and again."

Nick Clegg, the Liberal Democrat home affairs spokesman, also indicated his party would oppose measures to extend the limit, saying: "Twenty-eight days is already the longest period in any democratic jurisdiction in the world. Where on earth then is the evidence from the government that this further extension is necessary?"

Shami Chakrabarti, director of civil rights group Liberty, also opposed the plans, accusing the government was playing politics with security. "I for one still thought we were part of a constructive and friendly and ongoing process and then yesterday evening the process had stopped. "My interpretation of that being consensus is not actually sought."

As well as suffering a Parliamentary defeat on the matter under the leadership of Mr Blair, the Government's attempts to extend the pre-charge detention limit have run into numerous problems in the last few months.

Ken Macdonald, the director of public prosecutions, and Lord Goldsmith, the former Attorney General, have both questioned the extension.

In the most embarrassing development for the Government, Mr Brown's own security minister, Admiral Lord West of Spithead last month told BBC Radio 4's Today programme that he was not yet "fully convinced" of the need to raise the 28-day limit.

Barely an hour later, after a meeting with the Prime Minister, he emerged from No 10 with his position reversed, telling reporters: "My feeling is, yes, we need more than 28 days," he told reporters.

"I personally absolutely believe that within the next two to three years, we will require more than that for one of these complex plots. So I am convinced that’s the case, but it is very difficult because there is a civil liberties issue," he said.

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