Sept. 2 (Bloomberg) -- Ayman al-Zawahiri, top lieutenant to al-Qaeda leader Osama bin Laden, praised the July 7 attack on London's transport system in a videotape that also featured a message from one of the four suicide bombers.

Al-Zawahiri spoke about the reasons for the blasts that killed 52 people, describing them as ``a slap in the face to the policy of British Prime Minister Tony Blair,'' in the tape aired late yesterday by the Doha, Qatar-based al-Jazeera Television.

Muhammad Sadiq Khan, a 30-year-old British citizen from West Yorkshire who police identified as one of the bombers, explained his motivations for taking part in the bombings in English. He called himself ``a soldier'' adding ``we are at war'' and said no westerner should be safe.

At least two groups linked to al-Qaeda have claimed responsibility for the blasts in Internet statements whose authenticity haven't been verified. It wasn't immediately clear when or where the tape was recorded or why it was released only now. The two men were taped separately in what appeared to be different locations. Al-Zawahiri spoke standing next to a grenade launcher.

Al-Jazeera last broadcast a message from al-Zawahiri on Aug. 4, four weeks after the London blasts. A spokesman for the U.K. Foreign office said the government isn't commenting on any aspects of yesterday's video.

Police investigators had been searching for a wider network of people who supported, funded and masterminded the London attacks. A second bombing attempt on the transport system, which failed, followed on July 21.

Al-Zawahiri described the London attack as a ``conquest'' and compared it to those in Madrid last year and the U.S. in September 2001. The U.S. has offered $25 million for al-Zawahiri's capture.

``Your democratically elected governments continue to commit atrocities against my people all over the world,'' the man identified as Khan said. ``Until we feel security, you will be our targets. Until you stop the bombing, gassing, imprisonment and torture of my people, we will not stop.''

To contact the reporter on this story: Caroline Alexander in London at Calexander1@bloomberg.net.

Last Updated: September 2, 2005 04:35 EDT