LONDON - Mohammed Atta, the leader of the September 11 hijackers, is shown laughing and joking while filming his "martyrdom testament" as others involved in the terrorist attacks are filmed listening to a speech by Osama bin Laden in a newly released video.

The footage was taken at a camp used by bin Laden and senior al Qaeda figures in Afghanistan in January 2000 when some of the final details of the plan for the New York attack are said to have been put together.

Atta, who flew one of the planes into the Twin Towers, is seen alongside Ziad Jarrah, the pilot of the United Airlines flight 93, which crashed into a field in Pennsylvania.

It is the first time the two hijackers, who both appear to be studying their testaments which were due to be made public after their deaths, have been filmed together.

Also pictured, among the bin Laden audience, is Ramzi Binalshibh, reputedly the quartermaster and co-ordinator of the September 11 attacks who is now at Guantanamo Bay, and the al Qaeda leader's bodyguard Abu Jandal, who is also known as Nasir Ahmad Nasir al-Bahiri. Abu Jandal, jailed in Yemen until 2003, claimed he carried a gun to be used to shoot bin Laden if he was ever in danger of being captured.

The videotape, thought to have been obtained by Yosri Fouda, a journalist with Al-Jazeera television, is soundless and, according to United States security sources, lipreaders have not been able to decipher what was being said.

The filming is said to have taken place at Tarnak Farm, near Kandahar, where the CIA had once plotted to kidnap bin Laden with the help of tribal fighters. Atta, the son of an Egyptian lawyer, disappeared from his home in Hamburg in January 2000. Jarrah, who came from a middle-class Lebanese family, had also studied in Germany. The two men are seen sitting on the floor with a Kalashnikov rifle propped against a wall beside them. Atta wears a dark coloured sweater with horizontal stripes with a zipped collar. At one point he tries on a traditional Afghan hat before tossing it aside with a wry smile. Jarrah, wearing plastic framed spectacles, wears a long white robe.