Police have foiled 15 terror plots since 2000,

with suspects continuing to emerge from unexpected quarters, senior officers said .

The figure emerged as police backed the Government's controversial proposals to hold terrorist suspects for more than 28 days without charge.
Gordon Brown is facing a huge revolt over plans to push the limit to 42 days.
Critics include the former Attorney General Lord Goldsmith, who yesterday launched an extraordinary attack on the scheme, implying MPs should not "trust" the Home Secretary to implement safeguards.

But Sir Ian Blair, the Metropolitan Police Commissioner, told MPs the 28-day limit would be breached "sooner rather than later".
He said that suspects "suddenly emerge from left field" and have to be arrested at a very early stage, leaving officers with huge amounts of investigative work.
Sir Ian said: "We have reached a point where at 28 days we feel sooner or later - and maybe sooner - something is going to happen to make that insufficient."
Scotland Yard anti-terror chief, Assistant Commissioner Bob Quick, initially told the Commons Counter-Terrorism Bill standing committee that 15 plots had been foiled since the July 7 attacks in 2005.

This was later corrected to since 2000.
Several plots have already come to court and are known to the public.
They include plots to behead a British Muslim soldier and a fertiliser bomb attack on the Bluewater shopping centre in Kent.
Sir Ian indicated that he believed police were better placed than lawyers to know if 28 days was still sufficient.
But his comments are unlikely to persuade Labour rebels, who rejected a similar plea by Sir Ian in 2005 for terror suspects to be held for 90 days without charge.

Pictured: The day alleged 7/7 plotter met with the bombers at McDonalds

Up to 50 Labour MPs are preparing to vote against the Government - and they are likely to seize on remarks made yesterday by prosecutors.
Sue Hemming, head of the Crown Prosecution Service's counter-terrorism division, said the need to hold suspected terrorists for longer than 14 days had only been necessary on three occasions since the introduction of the 28-day limit in 2005.
Sir Ken Macdonald, the Director of Public Prosecutions, said he believed 28 days was "sufficient".

He added: "We have managed comfortably with 28 days."
Lord Goldsmith, who sat in Tony Blair's Cabinet, dismissed the Government proposal.
It would involve MPs and peers being asked to back a decision by the Home Secretary to raise the limit to 42 days in individual cases.
Lord Goldsmith said this was "not a great deal of a safeguard".
He asked the standing committee: "Are you going to ask Parliament to simply trust the Secretary of State?"

Call for vigilance: The Met's chief Sir Ian Blair warns that Britain is being threatened by extremists
Earlier this week, a leaked list from Labour Whips showed they expect at least 50 of their MPs to vote against the proposal.
A further 44 are said to be undecided.
With both the Tories and the Liberal Democrats against the scheme, Mr Brown is thought to on course for defeat in the Commons by around 20 votes.
Among the former ministers expected to rebel are Glenda Jackson, Frank Dobson and Michael Meacher.

Even some members of the Government are unhappy.
The Whips say Joan Ruddock, junior environment minister, believes the figure of 42 days has been "plucked from thin air" but she will vote in favour.
A Home Office spokesman said the Commons vote will be held in mid-June.