The FBI has said for the first time that some of the 19 suspected suicide hijackers responsible for the attacks on Washington and New York have links with Osama Bin Laden's al-Qaida network.
The claim - along with the first release of photos of the suspected hijackers - came as Pakistan sent an official delegation to Afghanistan in a last-ditch attempt to persuade the ruling Taleban to hand over Bin Laden.
The Taleban - which have said it would be against Islam to extradite Bin Laden - said on Thursday they had delivered a message to him, asking him to leave the country voluntarily.
Saudi-born dissident Bin Laden - a guest of the Taleban since 1996 - is suspected of being behind the suicide attacks on the World Trade Center in New York and The Pentagon on Washington on 11 September.
As thousands of Afghans fled their homes in fear of attacks by the United States, the US reiterated that it was in no hurry to go to war.
Defence Secretary Donald Rumsfeld said: "We're not leaping into this, we're moving into it in a measured way,"
Other officials said the US was focusing on investigating the attacks, on diplomacy and financial measures.
IN OTHER DEVELOPMENTS
FBI director Robert Mueller did not specify what the links between the hijackers and Bin Laden were.
And he admitted that the FBI is not certain about the identities of all the hijackers.
But he asked the public to come forward if they recognised any of the suspects, in the hope that questions about the true identities of some of them might be resolved.
"What we are currently doing is determining whether, when these individuals came to the United States, these were their real names or they changed their names for use with false identification in the United States," he said.
Friday's initiative will be Pakistan's second attempt to secure Bin Laden's handover.
The delegates will fly by special plane to the Taleban's Kandahar stronghold and return the same day.
They appear to be going as two missions - one diplomatic, endorsed by the Pakistani Government, the other religious.
The religious delegation is still waiting for the government, the international community or the Taleban to come up with proposals for talks.
A similar Pakistan team met the Taleban leadership in Kandahar last week, but failed to achieve a breakthrough.
The Taleban have failed to reveal the whereabouts of Bin Laden, although they said a message asking him to leave Afghanistan had now been delivered to him by hand.
The decision to ask him to leave was made a week ago.
But correspondents say he will find it difficult to leave Afghanistan because any country which accepts him will face the threat of American attacks.
SIX IN COURT
Earlier this week, Mr Bush announced the freezing of assets of 27 individuals and organisations - including al-Qaida - and urged world financial institutions to follow suit.
And on Thursday the US asked the UN Security Council to adopt a resolution obliging all member states to report within 60 days on measures taken to curb terrorist movements.
Six Algerians arrested in Spain on suspicion of links with Osama bin Laden will appear in court on Friday to face questioning in connection with an alleged terrorist plot against United States interests in Europe.
During the police operation, Spanish authorities seized videos belonging to the suspects which contained images of attacks in Algeria and Chechnya and training camps in Afghanistan.