Chancellor Gordon Brown has called for tougher security measures to tackle the threat of global terrorism.
The police followed up some 12,000 leads after 7 July, said Mr Brown
He said police should be given the power to detain terror suspects for more than 28 days without charge.
Speaking in London, he also defended the new offence of the glorification of terrorism, which MPs vote on this week.
He said three terror attacks had been thwarted against Britain since July. He also outlined plans for a National Veterans' Day and more cash for police.
His speech at the Royal United Services Institute came ahead of Monday evening's Commons votes on introducing identity cards, which are expected to be close.
He said the plans would prevent "one of the central features of terrorist activity", which is criminals' use of multiple identities.
One 11 September hijacker used 30 false identities to obtain credit cards and $250,000, he said.
"Since then the problem has, if anything, worsened," he said. "Over the last few years the major terrorist suspects arrested, typically, have had up to 50 false identities each."
He insisted that measures would be taken to ensure that a national identity database would not be abused by private companies or government departments.
"The legislation that comes before the Commons today already builds in important safeguards," he said.
"Private companies will not be able to see the national database, nor will government departments in routine business."
The issue of glorification of terrorism will go before MPs on Wednesday - and Mr Brown warned that opposition to the plans would "send the wrong signal".
He said no-one should be able to "publicly celebrate and glorify what happened in London" following the 7 July, 2005 bombings.
"If we withdraw glorification from the definition of indirect incitement, or from the grounds for proscribing organisations, as is being proposed by opponents this week, this would send the wrong signal that we could not reach a consensus on how serious this issue of glorification is."
But ex-Cabinet minister Clare Short, a friend of Mr Brown, said she thought the chancellor was "diminished" by the need to toe a Downing Street line.
She told BBC2's the Daily Politics: " "I think Gordon's got a real problem, I mean the party wanted him as an alternative to Blair as the country goes off Blair, but the longer it takes the more he has to stick up for everything Blair's done and be more like Blair ...
"It seems to be, from bits in the media, that the Number Ten machine is saying: 'Back everything Tony does, Gordon, and then we'll do an elegant handover to you', but I think that diminishes Gordon."
Hearts and minds
During his speech Mr Brown also said he was considering the possibility of a single security budget.
He said he was committed to fighting those who are secretly funding the terrorist threat.
And he called for a battle for the hearts and minds of British Muslims to prevent them coming under the influence of Islamic extremists.
He committed a total of £230m to counter-terrorism operations, including £75m for the Metropolitan Police and £135m for regional intelligence and investigation.
He also outlined plans for a National Veterans' Day to be celebrated each June with ceremonies in every constituency and the presentation of medals to veterans.