Tony Blair will use an emergency statement to Parliament today to make public for the first time Britain's "incontrovertible" evidence linking Osama bin Laden directly to the terror attacks in America.
The Prime Minister is expected to release carefully declassified intelligence as he seeks to persuade MPs that the case against Mr bin Laden and his al-Qa'ida network is unanswerable. In a move that will be interpreted as the precursor to military action, Mr Blair's statement to a recalled House of Commons would also send a powerful signal to potential allies in the Middle East that action has to be taken in Afghanistan.
Both the United States and Britain will step up their diplomatic efforts to seal the international coalition against terrorism with visits today to key states in the region.
Donald Rumsfeld, the US Defence Secretary, was in Saudi Arabia last night on the first leg of a hastily arranged tour aimed at shoring up support among Arab and Islamic members of the coalition. He will travel to Oman today. Mr Blair will fly to Moscow to meet President Vladimir Putin after his Commons statement.
The fresh round of shuttle diplomacy comes as reports in the US claimed last night that the Bush administration had prepared a military strike against Afghanistan on Tuesday but decided to call it off at the last minute.
Mr Blair was considering last night how much of the British case against Mr bin Laden he could release to the Commons, but senior government sources said he would "more likely than not" make public a limited version of the evidence. Both Britain and the US have spent weeks struggling to find a way of releasing their intelligence on the terrorists' links without jeopardising their security sources.
Iain Duncan Smith, the Conservative leader, infuriated some in the Government when he gave a strong hint of Mr Blair's intention after a briefing at Downing Street. In what one MP referred to as a "damaging gaffe", Mr Duncan Smith, who was made a privy councillor last month on becoming Tory leader, told reporters that the Prime Minister would have "something interesting" to tell Parliament. "I hope Parliament will take that opportunity to debate and discuss what he says in a positive way, not a negative way," Mr Duncan Smith said.
Charles Kennedy, the Liberal Democrat leader, was more circumspect after his own briefing from the Prime Minister but said he now accepted that there was "compelling" evidence against Mr bin Laden.
The US, which shared America's evidence against Mr bin Laden with Nato on Tuesday, asked its allies yesterday for military, intelligence and technical help to respond.
Although the list of requests remained secret, it included calls for support, intelligence-sharing, military bases, political and economic help in tracking terrorist cells and the right to use airspace. President Putin described the American request to Nato as "quite appropriate", adding: "We are familiar with the content of the list, of the issues and problems. There is no secret about this list in Russia."
The United States has started direct talks for the first time about military co-operation with the Afghan opposition, which has also been promised more arms and equipment by Russia and Iran. "I have met American officials face to face within the past several days," said Abdullah Abdullah, the foreign minister of the Northern Alliance.
The Afghan opposition would like to launch a ground offensive against the Taliban backed by American air power in the north of the country. Northern Alliance military commanders say they will not attack until the US does.
Mr Abdullah said the talks had focused on military co-operation, but he would not reveal where they were held. The most likely place is Dushanbe, the capital of Tajikistan.
US relations with the Northern Alliance require delicate handling because its leaders have repeatedly denounced Pakistan, another American partner, as the creator of the Taliban.
In the Middle East, Mr Rumsfeld will insist the target of US-British retaliation is purely the terrorists who carried out the 11 September attacks.
* The Indian authorities said that the reported hijacking of an internal Alliance Air flight between Bombay and Delhi last night was a false alarm, caused by a hoax telephone call and confusion on board the plane.Reuse content