Manhunt goes on as hijack tapes released

Senior US Administration sources yesterday confirmed that they have received "authoritative" intelligence information suggesting that Mohammed Atef, a senior al Qaeda leader, was killed by US bombing three days ago. Admiral John Stufflebeem told journalists that, if true, the death would have a significant impact on future al Qaeda operations. "I see that as one notch closer of the noose tightening," he said.

The hunt for Osama bin Laden intensified, they said, with US intelligence hoping to get access to senior Taliban leaders captured by the Northern Alliance to question them about his location.

More US special forces are being introduced to help with the search. The US Defence Secretary, Mr Donald Rumsfeld, said that he believes bin Laden is still in Afghanistan, but "if we knew his whereabouts, we'd have him".

Briefing journalists, he vigorously rejected suggestions that the Northern Alliance had been involved in "atrocities", insisting there was no evidence to that effect. Mr Rumsfeld said, however, that it was "perfectly acceptable" in a war to tell opponents that they must surrender or be killed.

Admiral Stufflebeem said that opposition forces control 60 per cent of the country. There was still strong resistance in Kunduz, while in Kandahar and Jallalabad the situation was still unclear.

Meanwhile American viewers have had a shocking reminder of the events of September 11th with the broadcast of the air-traffic control tape of the moments before United Airlines Flight 93 crashed in Pennsylvania.

In it the voice of one of the hijackers can clearly be heard saying: "Hi. This is the captain, I would like you all to remain seated. There is a bomb on board and we are going back to the airport. They have our demands..."

The recording also captured the sound of a struggle in the cockpit as the four attackers took control of the plane, and conversations between the aircraft and an air traffic controller in Cleveland.

Although the contents of the tape are widely known the actual sound of a series of routine communications and of fighting is chilling. Screaming can be heard, followed by an American voice shouting "Get out of here", believed to be the seizure of the cockpit. Later, the hijacker is heard telling passengers to remain seated, but his message is relayed accidentally to the ground rather than the back of the plane.

A second hijacker delivers a similar message over the aircraft's intercom. After the first message ground control asks other pilots to confirm if they have heard it.

Executive Jet 956 pilot chips in: "Centre, did you hear the transmission where the airplane just said he had a bomb on board? ... It sounded like someone said they had a bomb aboard." Controller: "That's what we thought. We just didn't get it clear."

Ground control asks: "United 93, please, do you still hear the centre?" It is a message they will repeat to no avail some 20 times.

Investigators have said transcripts of the cockpit voice recording reveal three passengers tried to overpower the men, but were unable to keep control of the aircraft.