Al-Qaeda carried out the July suicide bombings in London to strike at "British arrogance," the group's second man Ayman al-Zawahri said in a video tape aired on Arab satellite channel Al Jazeera on Monday.
"The London attack is one of the attacks that al Qaeda ... had the honour of carrying out against ... British arrogance, the aggression of the crusader British against the Muslim nation for over a hundred years," Zawahri said.
He denounced Britain for "the historical crime of setting up Israel and the continuing crimes in Afghanistan and Iraq.
"These and other attacks have revealed the true hypocritical face of Western civilisation that talks about human rights and freedom only as long as it is in its interest," he said, citing the planned toughening of British security laws after the London blasts.
A U.S. counterterrorism official said the tape was "al Qaeda's clearest public statement to date suggesting that they were responsible (for the London attack). But that in and of itself does not prove that al Qaeda planned or directed the attack. They're quite happy to take responsibility for any terrorist attack."
The U.S. official, who said the tape was still being reviewed by intelligence officials, said it was "still unclear what the nature and extent of their involvement (in London) was."
Zawahri denounced elections in Afghanistan, saying they were not free and were carried out under U.S. occupation. "These elections are a farce more than anything else," he said.
He insisted the Taliban were still powerful and said U.S. forces had to "hide" in their bases, reports Reuters.
Zawahri, shown wearing a turban and talking to someone off-screen, said the "blessed" London attacks were targeted at "the British Crusader's arrogance and against the American Crusader's aggression on the Islamic nation for 100 years".
He denounced Britain for "the historical crime of setting up Israel and the continuing crimes in Afghanistan and Iraq".
Zawahri also criticised the British government's plans to deport the radical Jordanian cleric Abu Qatada and nine other foreign nationals said to be a threat to UK security.
Plans to toughen the UK's anti-terror laws following the bombings showed "the dreadful colonial face of Britain", he said, informs BBC.
Still: Al Jazeera
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