Al-Qaeda deputy leader Ayman al-Zawahri threatened more destruction in London, saying in a videotape broadcast Thursday that British Prime Minister Tony Blair would be to blame.
Al-Zawahri also threatened the United States with tens of thousands of military dead if it does not withdraw its troops from Iraq immediately.
The tape, aired on the pan-Arab satellite channel Al-Jazeera, was delivered exactly one month after the July 7 bombings in London that killed 56 people, including four suicide attackers.
Also read: The London Blasts
"Blair has brought to you destruction in central London, and he will bring more of that, God willing," al-Zawahri said in the tape, referring to the July 7 and July 21 attacks on London's subways and buses.
In London, Blair's Downing Street office declined to comment on the broadcast.
Al-Zawahri, an Egyptian doctor who merged his militant faction with that of al-Qaeda leader Osama bin Laden in Afghanistan in the late 1990s, spoke with a Kalashnikov rifle propped up behind his right shoulder against a plain background.
He has been in hiding since the United States invaded Afghanistan in late 2001.
In the latest videotape, al-Zawahri warned the United States it could expect significantly more casualties from its military campaigns in Iraq and Afghanistan.
"As for you, the Americans, what you have seen in New York and Washington, what losses that you see in Afghanistan and Iraq, despite the media blackout, is merely the losses of the initial clashes," he said, referring to the Sept. 11 attacks blamed on al-Qaeda.
"If you go on with the same policy of aggression against Muslims, you will see, with God's will, what will make you forget the horrible things in Vietnam and Afghanistan."
He then addressed Americans, saying, "The truth that has been kept from you by (President) Bush, (Secretary of State Condoleezza) Rice and (Defense Secretary Donald H.) Rumsfeld is that there is no way out of Iraq without immediate withdrawal, and any delay on this means only more dead, more losses.
"If you don't leave today, certainly you will leave tomorrow, and after tens of thousands of dead, and double that figure in disabled and wounded."
Referring to the Western nations contributing troops to the US-led coalition in Iraq, he said: "As to the nations of the crusader alliance, we have offered you a truce if you leave the land of Islam.
"Hasn't Sheik Osama bin Laden told you that you will not dream of security before there is security in Palestine and before all the infidel armies withdraw from the land of Muhammad?" al-Zawahri added.
"Instead (of accepting the truce), you spilled blood like rivers in our countries and we exploded the volcanoes of wrath in your countries."
He did not name any countries apart from Britain, but he appeared to be referring to the terror attacks in Madrid, Spain, last year that were linked to al-Qaeda.
"Our message is clear: you will not be safe until you withdraw from our land, stop stealing our oil and wealth and stop supporting the corrupt rulers," al-Zawahri said.
The tape showed al-Zawahri positioned in front of a woven cloth that moved with the wind and showed the sunlight,indicating it appeared to be made outdoors. He was wearing a white robe and a black turban and emphatically wagged his finger at the camera while speaking.
In June, Al-Jazeera broadcast a videotape of al-Zawahri disparaging the U.S. concept of reform in the Middle East and saying armed jihad was the only way to bring change in the Arab world.