Briefing reporters on Blair's weekly cabinet meeting, he said Home Secretary Charles Clarke had started "an immediate review of his powers to exclude people from this country who are likely to incite terrorism".

He said Clarke, as the senior minister in charge of public security and immigration, already has the authority to ban foreigners from Britain "if their presence is not conducive to the public good".

"Fourteen people were excluded in 2004 on that basis, 12 of them on national security grounds," Blair's spokesman said.

"This included a radical Pakistani cleric who was in the country on a visitor's visa and who spoke at a mosque in Glasgow to encourage jihad," he said, without identifying the cleric.

He said Clarke, as part of his review, was considering how Britain might "automatically" react to the exclusion of a foreigner by another country, such as the United States or an EU member state.

Clarke is also considering whether to slap conditions on asylum-seekers and those given the right to stay permanently in Britain, expressly prohibiting them from inciting terrorism.

Blair's spokesman said the prime minister would be meeting in the coming days with police and intelligence chiefs, Muslim community representatives, and leaders of the main opposition parties to seek a consensus on the "pace and content" of new anti-terrorist legislation.

Britain's core anti-terrorist law remains the Terrorism Act 2000, but it is to be complemented next year by legislation that would outlaw both "acts preparatory to terrorism" and condoning terrorism.

Fifty-two people are confirmed dead, and hundreds injured, after three Underground subway trains and a double-decker bus were attacked last Thursday by four apparent British-born suicide bombers.

Blair has linked the attacks to Islamic extremists and Osama bin Laden's Al-Qaeda organisation, as police step up their hunt for those who masterminded the bloodiest attacks on British soil since World

War II.