The UK's most senior police chief said there was "chilling" evidence of new terrorist plots as he urged support for new powers to detain terror suspects.

Metropolitan Police chief Sir Ian Blair said police should be able to hold suspects without charge for 90 days.

His warning came as the government said it was increasingly confident it would win an MPs' vote on the new time limit.

But the Tories, Lib Dems and some Labour MPs say 28 days' detention is the maximum they will accept.

Government officials admit the numbers ahead of the vote on Wednesday are very tight.

'No auction'

The proposal to extend the detention time limit from 14 to 90 days originally came from the police and Sir Ian used a lunch with political journalists at Westminster to reinforce their case.

He said the police were "not in an auction" over the plan but believed 90 days was the right length of time needed because of the complexity and mass of evidence in terrorism cases.

Should terror suspects be held for 90 days?

In pictures

"I do accept what we are putting forward is unknown in peacetime," he said.

"But I have never seen anything like what's happening at the moment. There are people out there in the UK plotting mass murder without warning.

He said he had thought hard about whether the police had entered a political debate.

But he said: "This is not in my view politics. This is our professional opinion."

Sir Ian said 90 days was not a "magic" figure and four months might be better.

'Political pawns?'

But Tory leader Michael Howard said: "The logic of what they are saying is that there shouldn't be any limit at all and that we should have quite unlimited detention without charge."

That was unacceptable, he added.

Alistair Carmichael, the Liberal Democrats home affairs spokesman, warned the Metropolitan Police to be careful about entering a political debate.

Letter from Met Police to Home Secretary (2.44MB)
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"On such a controversial matter and at such a politically sensitive time, they need to tread very carefully when intervening in public," he said.

"Because the government is no longer trusted, they are all too keen to see the police take a lead in this debate.

"But any suggestion that they are being used as political pawns would only serve to undermine confidence in both the police and in the political process."

Last week, Home Secretary Charles Clarke promised to hold talks on the issue when the 90-day proposal faced a possible Commons defeat.

But ministers are now sticking by their original plan, although they also have a "fall back" position of 60 days.

Brown intervention

Tony Blair's official spokesman said on Tuesday: "There is a growing acceptance for 90 days but the government takes absolutely nothing for granted."

And Chancellor Gordon Brown backed the plan in his first public comments on the issue.

Mr Brown said he was "shocked and surprised by the short-term opportunism" of the Conservatives.

People have to face up to an issue which exists now because of a terrorist threat which is real and substantial
Charles Clarke
Blair puts leadership on the line

Clarke's statement

He accused leadership contenders David Cameron and David Davis, for failing to put the advice from the security services first.

Mr Davis, the shadow home secretary, called that suggestion "laughable".

"If you are trying to be opportunist, you support the popular side, populist side of an argument, not the unpopular side, he said.

"Three-quarters of the British people support Blair's proposal for 90 days.

"What we're arguing is this is a matter of high principle - that hundreds of thousands, if not millions, of people died to defend the right to presumption of innocence, the right not to be locked up without trial."


Some Conservative MPs, including former minister Ann Widdecombe, say they will vote for the government's 90-day proposal.

But Lib Dem leader Charles Kennedy predicted ministers would not get the 90-day plan through Parliament.

"It is reprehensible and regrettable that the prime minister is just throwing consensus out of the window - or indeed any genuine efforts to achieve consensus," said Mr Kennedy.

MPs will on Wednesday vote on an amendment, introduced by Labour backbencher David Winnick, calling for the 28-day compromise.