NATO secretary-general George Robertson has said the US has provided "clear and compelling evidence" that Saudi dissident Osama bin Laden was responsible for last months attacks in the United States.
Mr Robertson said the US submitted the evidence during a classified briefing to its NATO allies.
"It is clear that all roads lead to Al-Qaida and pinpoint Osama bin Laden as having been involved in it," he said.
However, the US has refused to reveal the alleged evidence to the general public and has even refused to reveal it to Afghanistan’s Taliban Government, which is sheltering bin Laden.
The Taliban has said bin Laden could be extradited if the US provides conclusive evidence of his involvement in the US attacks.