The video included footage from armed groups and Western television stations, including critical remarks on the US strategy in Iraq by Ricardo Sanchez, the former senior US commander in Iraq.

Al-Zawahiri dismissed optimism expressed by Washington, saying: "Either the US administration is lying outrageously ... or the Americans have not learned anything from four years of war, as they did not learn from their defeat in Vietnam."

'American plots'

The senior al-Qaeda leader also condemned attacks on "innocent" Iraqi civilians by armed groups and called for a swift investigation.

"...the Americans have not learned anything from four years of war, as they did not learn from their defeat in Vietnam"

Ayman al-Zawahiri, deputy leader of al-Qaeda

He alleged foreign agents might have infiltrated the ranks of the Islamic State in Iraq organisation, which is affiliated with al-Qaeda, to commit crimes in its name and drive Sunni groups to ally themselves with US-led forces.

"If it becomes clear that some group is involved in these crimes, they should be exposed to defeat the plots of the Americans," he said, calling on Sunni groups to unite with the Islamic State in Iraq group.

Websites, which published the video, invited sympathisers to send in questions for al-Zawahiri to answer in an "open interview" next month.

Al-Zawahiri went on to denounce Iran for "stabbing the Islamic nation in the back" by recognising the US-backed government in Iraq and "empty propaganda" against Israel.

"Were [the Iranian president] sincere about eliminating Israel, he would not remain with it as a member of the United Nations, whose charter defends the sovereignty, territorial integrity and well-being of all members," al-Zawahiri said.

The 97-minute video, subtitled in English, was dated Dhu al-Qidah, the month in the Muslim lunar calendar which ended on December 10.

Al-Zawahiri called on Muslims to support al-Qaeda's wing in north Africa, which set off two bombs in Algeria's capital last week.

He also urged Pakistan's army and devout Muslims there to rise against Pervez Musharraf, the US-allied president.