Bin Laden tape: Hijackers told of plot as they boarded planes

On a translated tape released by the US Defence Department today, Osama bin Laden says ‘‘we calculated in advance’’ the number of casualties in the September 11 attacks.

He also said ‘‘we did not reveal’’ the attack plan to the hijackers until ’’just before they boarded the planes.’’

Bin Laden laughed and boasted in a video that the collapse of the World Trade Centre exceeded his expectations.

The recording, released by the US government today, apparently showed the al-Qaida leader grinning as he told guests at a dinner in Afghanistan that the suicide hijackers had only learned they were going to their deaths before they boarded the planes.

He told them how he had listened to the radio, waiting for news of the attacks, then celebrated afterwards with his ‘‘brothers’’.

The tape was found by American intelligence agents at a house in Jalalabad, and was shot at a dinner with other Taliban and al-Qaida leaders in a house in Afghanistan, the Pentagon said.

Today it was finally released by the Pentagon four days after its existence first emerged, with a translation of everything that is audible on the amateurishly-shot home video.

The Saudi dissident said he expected the planes to destroy four storeys of the towers on impact, but added that he was surprised when he heard the towers had completely collapsed.

He said he only expected the sections of the towers above the impact zone to collapse and revealed how he predicted that the burning gas from the planes would melt the metal holding the buildings upright.

He said: "This is all that we had hoped for.

"We had notification since the previous Thursday that the event would take place that day. We had finished our work that day and had the radio on. It was 5.30pm our time. Immediately we heard the news that a plane had hit the World Trade Center. We turned the radio station to the news from Washington. The news continued and no mention of the attack was made until the end.

"After a little while, they announced that another plane had hit the WTC. We were overjoyed by it."