Ayman al-Zawahiri, Osama bin Laden's deputy, insisted that the London suicide bombings were the direct result of the Prime Minister's decision to join the US-led invasion of Iraq. The statement, in a videotape broadcast by the Arab satellite channel al-Jazeera, was the first message from al-Qa'ida since the London blasts.
It came on a day that London had braced itself for more possible bombings, with 6,000 police patrolling the streets and transport system. The first person to be charged over the bombings, Ishmael Abdurahman, also appeared in court in London.
Zawahiri, speaking with a Kalashnikov next to him, said: "Blair's policies brought you destruction in central London and will bring you more destruction, God willing." He went on to promise attacks on Americans "that will make you forget the horrors you have seen in Vietnam".
Al-Qa'ida's second-in-command stopped short of claiming responsibility for the London blasts. However, he said that Britain, the US and other countries with troops in Iraq would face unremitting hostilities. "You spilled blood like rivers in our countries and we exploded volcanos in yours. Our message is clear, strong and final; there will be no salvation until you withdraw from our land, stop stealing our oil and resources and end support for infidel, corrupt [Arab] rulers," he said.
Wearing a white robe and black turban, Zawahiri, regarded as Bin Laden's spiritual mentor and closest adviser, accused the US administration of falsifying losses in Iraq and Afghanistan. "The truth that has been kept from you by Bush, Rice and Rumsfeld is that there is no way out of Iraq without immediate withdrawal, and any delay on this means only more dead and more losses."
Zawahiri's linking of Mr Blair's foreign policy to the London bombings follows claims by Hussain Osman, the suspect in the 21July attempted bombings under arrest in Rome, that he and his accomplices were motivated by the suffering of Muslims in Iraq. Mr Osman, who is being held in Italy on a European arrest warrant, will face a hearing there on 17 August to decide if he can be extradited to the UK.
Downing Street refused to comment on the al-Qa'ida warning. Mr Blair is reported to have asked ministers to cut short their summer holidays for an emergency cabinet meeting.
The Liberal Democrat foreign affairs spokesman, Sir Menzies Campbell, said: "No one should be surprised that they would try to exploit the attacks in London. Whatever the motives of those responsible for the July attacks, the primary task is now to continue with investigations."
The shadow Home Secretary, David Davis, said: "We know the British people will treat this with the contempt it deserves and that they will continue to show the resilience and courage that has been so impressive since the atrocities in London."
President George Bush said last night threats from al-Qa'ida's second-in-command would not drive the US out of Iraq or the Middle East."As I have told the American people, the people like Zawahri have a ideology that is dark, dim, backwards," Mr Bush said."We will stay the course, we will complete the job in Iraq."
He added: "The Iraqis want to live in a free society. Zawahiri doesn't want them to live in a free society. And that's the clash of ideologies: freedom versus tyranny. We have had these kinds of clashes before and we have prevailed."
Mr Bush said US troops would remain in Iraq until Iraqis are sufficiently trained to defend themselves, but he gave no timetable for this. " They're terrorists and they're killers and they will kill innocent people ... so they can impose their dark vision on the world," he said.
A CBS News poll on Wednesday said 55 per cent of Americans did not approve of the way Mr Bush was handling the Iraq war, compared with 41 per cent who approved. Forty-six per cent of Americans believed Mr Bush should decrease the number of US troops there, and 59 per cent said the war had not been worth the cost in lives and money.
An AP-Ipsos poll this week showed support at just 38 per cent. A year ago, the public was evenly divided on Iraq. Mr Bush has lost support most dramatically among younger women, especially those who live in the suburbs, and among less-educated men. Despite the horrific headlines, many military analysts say attacks on US troops have actually remained constant in recent weeks while attacks on Iraqi civilians have increased.
Zawahiri, the Egyptian eye surgeon, 54, is credited with being the " mastermind" behind the 11 September 2001 attacks on the US. He has been sentenced in Egypt in absentia to death and has a US bounty on his head of $25m (£14.4m).
He is believed to have linked up with Bin Laden while they were living in Khartoum, Sudan. His last confirmed sighting was in Khost, Afghanistan, four years ago, where his wife and children were reportedly killed in a US air strike in November 2001.
As for the English, I say to them: Blair has brought destruction upon you, to the centre of London, and he will have more of it, Allah willing.
Oh the peoples of the Crusader coalition, we have offered you, at least, to stop your aggression against the Muslims ... The lion of Islam, the mujaheed sheikh Osama bin Laden, may Allah protect him, has offered you a truce, so you will leave the lands of Islam. Did sheikh Osama bin Laden not tell you that you could not dream of security before we live it as a reality in Palestine and before all the infidel armies leave the land of Muhammad?
But you have made rivers of blood in our countries, so we blew up volcanoes of rage in your countries. Our message to you is clear: You will not be saved unless you withdraw from our land, stop stealing our oil ... and cease your support of the corrupt (Arab) rulers.
Oh Americans, what you have seen in New York and Washington, and the casualties you witness in Afghanistan and in Iraq ... are nothing but the casualties of the initial clashes. If you continue the same policy of aggression against Muslims, you will see, Allah willing, horrors that will make you forget what you saw in Afghanistan... I mean, in Vietnam.
A fact that [George] Bush, [Condoleezza] Rice and [Donald] Rumsfeld conceal from you is that there is no way out of Iraq other than immediate withdrawal, and that any delay in making this decision means nothing but more dead ... If you don't leave today, you will definitely leave tomorrow, but with tens of thousands of dead ...