Mr Tony Blair says he has seen "powerful and incontrovertible evidence" of Osama bin Laden's link to the terror attacks on New York and Washington on September 11th.
With British special forces already on the ground in Afghanistan, the Prime Minister's comments fuelled expectations of a powerful opening strike any time now against bin Laden and his network of support.
And with Parliament recalled for Thursday, the gathering international crisis over-shadowed the opening of the Labour Party conference in Brighton, where delegates gathered amid unprecedented levels of security.
An estimated 1,000 anti-capitalist and anti-war demonstrators - far fewer than expected by Sussex police - took part in a demonstration along the seafront yesterday afternoon.
After a sombre opening with a two minute silence in honour of those who died in the American atrocities, the Deputy Prime Minister, Mr John Prescott, predicted Mr Blair would win "unanimous support" from the conference for his "shoulder to shoulder" fight alongside President Bush against global terror.
Mr Blair did not travel to Brighton for the customary conference preliminaries and his speech tomorrow is expected to be dominated by the crisis and impending commitment of British forces to military action.
Yesterday, in an interview with the BBC's Breakfast with Frost programme, Mr Blair said: "Yes, I have seen absolutely powerful and incontrovertible evidence of his (bin Laden's) link to the attacks in America."
And Mr Blair again said that if the Taliban regime refused to give him up then they would become "an obstacle that we have to disable or remove . . ." The British government shared American scepticism last night about Taliban claims to have bin Laden under control.
Speaking in Brighton, the Europe Minister, Mr Peter Hain, said he was treating such claims "with a great deal of caution", insisting "he must be surrendered" to enable international justice to take its course.
Mr Blair confirmed MPs will be asked within weeks to approve drastic new measures designed to ensure Britain does not serve as a "safe haven" for terrorists.
Emergency Bills to be brought before parliament in the new session are expected to include new fast-track extradition provisions, and measures to toughen asylum laws and tackle the problem of money laundering.
At the same time the Home Secretary, Mr David Blunkett, is understood to be planning to make incitement to religious hatred an offence in an effort to curb both Muslim extremists and white racists in Britain.
"We cannot have a situation where it takes years to extradite people," said Mr Blair.
"We cannot have a situation in which people come in and abuse our asylum procedures and are then allowed to remain in this country claiming asylum."
However the first test of the new international anti-terrorist regime is presented by the case of the Algerian pilot, alleged to have been the "lead instructor" for the hijackers of the four American planes on September 11th.
His fight against extradition to America in the British courts could last, it has been estimated, anything up to three years.
It was not immediately clear if Mr Blair's new legislation would be retrospective and apply to persons currently facing extradition proceedings.