President George W Bush has hailed as a "serious blow" the capture of a top al-Qaeda suspect alleged to have planned the 11 September attacks.
The US hopes more arrests will follow
"The terrorists are learning there is no place safe for
them in this world, " Mr Bush said, in his first public comments since the arrest of Khalid Sheikh Mohammed at the weekend.
Pakistan says Sheikh Mohammed is now in US custody at an American military air base in Afghanistan.
Information Minister Sheikh Rashid Ahmed said the Kuwaiti-born suspect had been handed over with permission from the Kuwaiti Government.
The information minister said Pakistani interrogators had extracted all the intelligence they needed from Sheikh Mohammed.
US officials say one of the two other men captured with Sheikh Mohammed helped to fund the 11 September hijackings.
He has been named as Mustafa Ahmed al-Hawsawi in the US media.
The third man is a Pakistani national, Ahmed Abdul Qadus.
A Pakistani army officer related to him is being questioned in connection with the arrests, a presidential spokesman told the BBC.
The spokesman said it was a routine matter.
White House officials hope that more arrests will follow soon.
They say computers, mobile phones and documents found during Saturday's sweep might well lead to substantial additional information on al-Qaeda's plans and operations.
And President Bush is not hiding his pleasure at the latest developments.
"The man who masterminded the 11 September attacks is no longer a problem," Mr Bush said, referring to Sheikh Mohammed as al-Qaeda's "top operational planner" and "top killer".
Washington is hoping that the suspect can lead them to Osama Bin Laden and to sleeper cells in the United States.
It has also been suggested that he was involved in the murder of US journalist Daniel Pearl in Karachi last year.
On Tuesday, Australia said it wanted to question Sheikh Mohammed in connection with last October's bombings in Bali, in which more than 200 people were killed, including 89 Australians.
Australian Foreign Minister Alexander Downer said the country wanted to find out if he had any links to Jemaah Islamiah, the Asian Islamic group blamed for the Bali bombings.
A French judge has also issued an arrest warrant for him
in connection with a suicide bomb attack on a Tunisian synagogue last year, justice officials in Paris said.
The blast killed 14 German tourists, four Tunisians and a French citizen.
Trail to Rawalpindi
Washington has described Sheikh Mohammed as one of al-Qaeda leader Osama Bin Laden's "most senior and significant lieutenants".
A spokesman for President Pervez Musharraf described him as "the kingpin of al-Qaeda".
The New York Times reported that it was the capture of Muhammed Abdel Rahman during a raid on an apartment in the Pakistani town of Quetta on 13 February that led to this weekend's arrest.
The whereabouts of Bin Laden remain unknown
Mr Rahman - the son of the blind Egyptian cleric accused of inspiring the 1993 bombing of the World Trade Center - is alleged to have told investigators that Sheikh Mohammed had lived at the same Quetta address.
From there, Sheikh Mohammed was reportedly tracked to Rawalpindi, where he was captured in a bloodless operation.
Sheikh Mohammed has been indicted in America for plotting to blow up American commercial airliners in the Philippines in the mid-1990s.
Sheikh Mohammed has long been on the FBI's most-wanted list, and the US had recently increased the reward for his capture to $25m.
BBC Pentagon correspondent Nick Childs says the Bush administration has been under pressure at home from critics who complain it has neglected the hunt for al-Qaeda as it focused on Iraq, and the arrest will take some of that heat off.
US intelligence agents have been hunting remnants of Afghanistan's former Taleban regime and Bin Laden's al-Qaeda network since the US-led military action in Afghanistan in late 2001.
Hundreds of al-Qaeda militants and former Taleban leaders are thought to have fled into Pakistan since US-led forces launched the strikes following the 11 September attacks.