Osama bin Laden says he is committed to a "Holy War"
US officials have described the Saudi-born dissident as their chief suspect in off-the record briefings, saying they have intercepted messages between his people talking about the attacks.
The Taleban ambassador to neighbouring Pakistan, Abdul Salam Zaeef, said, when asked about Mr Bin Laden's possible extradition, that the first step would be to discuss any US evidence.
"If any evidence is presented to us, we will study it," he told reporters.
"About his handover, we can talk about that in the second phase," Mr Zaeef said.
BBC World Affairs editor John Simpson says the ruling militia has consistently maintained that allowing Mr Bin Laden to remain in the country was a matter of honour.
A reversal could mean that Afghanistan's leaders are trying to rescue themselves from an all out, massive attack by American forces.
Mr Bin Laden has denied involvement in the attacks on the United States, but says he fully supports such "daring acts".
Attacks
US investigators blame Mr Bin Laden for the car bombings that killed 224 people at the US embassies in Kenya and Tanzania and last year's bomb attack on the USS Cole at a harbour in Yemen, which killed 17 US sailors.
He has repeatedly denounced the United States for sending troops to Arab countries and for its support of Israel.
But in a statement apparently sent from somewhere in Afghanistan and published by a Pakistani newspaper considered close to Mr bin Laden, the Saudi dissident has been quoted as saying that even if he was eliminated, such attacks were not going to stop.
He was reported to have praised what he called the courage of the suicide attackers, and thanked God.
'Noble cause'
The United States would get nothing out of eliminating one Osama, the paper quoted him as saying, " as there were several Osamas".
He said dozens of known fighters and other experts were with him and were willing to give their lives for what he described as a "noble cause".
However, BBC World Affairs Correspondent John Simpson said that there was "not a lot of doubt" that Mr Bin Laden was involved.
"There is no one else that has the flair for terrorism and his men have targeted the World Trade Center before."