A man captured with an alleged al-Qaeda mastermind in Pakistan helped to fund the 11 September hijackers, US officials say.
Abdul Qadus was detained along with Sheikh Mohammed
US media reports name the man as Mustafa Ahmed al-Hawsawi and say he could be another important catch.
Mr Hawsawi was arrested in the same pre-dawn raid by US and Pakistani forces which netted Khalid Sheikh Mohammed and Abdul Qadus.
Sheikh Mohammed - said to be a senior al-Qaeda leader - has been flown out of Pakistan, probably to be interrogated at a US detention facility at Bagram air base in Afghanistan.
US President George W Bush broke a public silence on the Rawalpindi arrests on Tuesday, saying the action "struck a serious blow" against Osama Bin Laden's network.
While Sheikh Mohammed and Mr Qadus were named soon after they were captured, the third man was not identified beyond the fact that he was of Middle Eastern origin.
But US media have now quoted US intelligence officials as saying he is Mr Hawsawi.
The Saudi-born Mr Hawsawi, 34, has been listed as a "supporting conspirator" for Zacarias Moussaoui, the alleged "20th hijacker" who was set to take part in the attacks on New York and Washington.
In the charges against Mr Moussaoui, US officials allege that Mr Hawsawi:
- Opened bank account for Fayez Ahmed, who was one of the hijackers who flew the second plane into the World Trade Center
- Deposited money for the hijackers' use
- Received refunds from hijackers including alleged ringleader Mohammad Atta in the days before the attacks
- Fled the United Arab Emirates for Pakistan on 11 September, 2001, the day of the attacks
Officials hope that the capture of Mr Hawsawi and Sheikh Mohammed, accused of planning the 11 September attacks, will help them in their investigation as well as provide information on the whereabouts of Bin Laden and any sleeper cells in the US.