A chilling message to Britons· Al-Qaida blames Blair and threatens more attacks
· They are dark, dim and backwards, says Bush
The second in command of Osama bin Laden's al-Qaida network issued a chilling warning of further attacks in the UK and America yesterday and blamed Tony Blair's involvement in the Iraq war for the atrocities in London on July 7.
In a broadcast aired by al-Jazeera television exactly four weeks after blasts that killed 56 and injured hundreds, Ayman al-Zawahiri said that the prime minister's "policies brought you destruction in central London and will bring you more destruction".
Neither Downing Street nor the Foreign Office would comment, but the message drew a sharp response from George Bush from his ranch in Texas.
He said: "The comments by the number two man of al-Qaida make it clear Iraq is a part of this war on terror, and we're at war ... the people like Zawahiri have a ideology that is dark, dim, backwards. He's threatening. They have come up against a nation that will defend itself."
He added: "We've had these kinds of clashes before and we have prevailed. We will stay the course. We will complete the job in Iraq."
Al-Zawahiri, who was filmed against a brown cloth backdrop with a rifle propped at his side, stopped short of claiming responsibility for the July 7 attacks. Wagging his finger in the direction of the camera, he said: "Blair's policies will bring more destruction to Britons after the London explosions."
He told the US: "If you continue the same hostile policies you will see something that will make you forget the horrors you have seen in Vietnam.
"There is no way out for Washington except by immediate withdrawal. Any delay in this decision means more killing and losses. If you don't withdraw today, you will inevitably withdraw tomorrow, but only after tens of thousands are killed and injured."
Referring to a truce offer made by "our blessed Sheikh Osama" to the "crusader coalition" in April last year, he continued: "You will not dream of security until we live it as a reality in Palestine and until all your infidel armies leave the Prophet Muhammad's lands.
"Our message to you 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 [Muslim] rulers."
Al-Zawahiri has figured in at least six video or audio tapes since September 11 2001. Before yesterday, his most recent video broadcast by al-Jazeera was in June when he called for armed struggle to expel "crusader forces and Jews" from Muslim countries.
Disparaging American attempts to promote reform in the Middle East, he said peaceful change was impossible.
An Egyptian-born doctor, al-Zawahiri is an Islamist militant whose faction merged with that of Bin Laden in Afghanistan in the late 1990s. Bin Laden last appeared in a video in October.
The intelligence services have found no evidence that the attacks in Britain were either organised or coordinated by al-Qaida, but the organisation has proved itself to be media savvy with carefully timed broadcasts that have indirectly linked them to previous high-profile attacks.
The threats came amidst a major police operation in the capital involving thousands of armed officers and dozens of SAS troops. While there was no specific intelligence about further bombings, both July 7 and July 21 were Thursdays. This led to yesterday's huge security effort, particularly in the capital where random stop-and-search operations were carried out.
Detective chief constable Andy Trotter, of the British transport police, said: "This is the biggest threat London has faced in peacetime and we have to throw all our resources into it right now ... There is a tendency to talk about Thursdays, but obviously we cannot afford to become predictable."
Scotland Yard sources said yesterday that the release of information by the New York police commissioner, Raymond Kelly, about how the July 7 bombs were made was "unsanctioned". There were "elements of accuracy" in what Mr Kelly had said but "a lot of speculation, too".
The New York police department admitted last night that information revealed about the bombings in London had not been cleared for release by the British authorities.
The sources denied, however, that the latest leak from the other side of the Atlantic had created a major row between the two forces. American officers have been working closely with Scotland Yard on the inquiry and have been privy to many of the key briefings.
Mr Kelly suggested that hair bleach and citric acid had been used in the bombs which had been stored in a commercial grade refrigerator in the home of one of the bombers in Leeds. He said it appeared that the bomb recipe had been as easy to obtain from the internet as "a recipe for meatloaf".
He told New York security chiefs the bombs had been transported in coolers in a car to Luton en route for London. He also said that the bombs had been detonated by the alarms on mobile phones.
Explosives expert Hans Michels of Imperial College said yesterday that suicide bombers would not need timers. If they had been used, he said, it raised new questions about the July 7 bombers.
"Given that the bombers all had their personal documents with them and that they had apparently bought return tickets [to] Luton, this leaves another chilling thought," he said. "Whether planned or not ... dead terrorists leave fewer traces."