Mohammed is the third senior al-Qaida figure to be arrested in Pakistan. He was taken Saturday in Rawalpindi, a city near the Pakistani capital of Islamabad, Information Minister Sheikh Rashid Ahmed said. 

CIA officers and Pakistani authorities carried out the operation that led to Mohammed's capture, according to American officials, who spoke on condition of anonymity. 

Pakistan has handed other al-Qaida suspects over to the United States but neither Pakistani nor U.S. officials would not say whether that was the plan this time. 

"This is a great success today, but the war on terrorism goes on tomorrow," said Jim Wilkinson, a spokesman at U.S. Central Command in Tampa, Fla. "There's still a lot of work to do." 

U.S. officials say Mohammed organized the Sept. 11, 2001, terror mission that sent hijacked passenger jets crashing into the World Trade Center, the Pentagon and a field in Pennsylvania, killing more than 3,000 people. 

But even before then, Mohammed was wanted in connection with plots in the Philippines to bomb trans-Pacific airliners and crash a plane into CIA headquarters. Those were broken up in 1995. 

He also has been linked to April's bombing of a synagogue in Tunisia. At least 19 tourists, mostly Germans, were killed then. 

Mohammed was arrested along with an unidentified man of Middle Eastern origin and a Pakistani identified as Ahmed Abdul Qadoos, a 42-year-old member of one of the country's main religious parties, Jamaat-e-Islami. 

Mohammed narrowly escaped capture in a raid about a week ago in the southwestern town of Quetta, a Pakistani government source said. During that raid, a Middle Eastern man, possibly of Egyptian origin, was arrested, according to the source, who spoke to the AP on condition of anonymity. 

"At the time of that raid in Quetta the authorities were looking for Khalid Shaikh but he escaped and from there they followed him to Rawalpindi," the official said. "They got information from the man they picked up in Quetta and from phone calls until they tracked him down to Rawalpindi." 

Senior government officials said the three men were arrested about 3 a.m. local time Saturday at a house where Qadoos lives with his father. 

But Omar Qadoos, Ahmed's cousin, said only Ahmed, his wife and two children were in the house. There also was a guard outside, he said. 

"The police pounded on the gate and then they rushed through. There was some firing, but no one was hurt and then they beat the guard and broke the lock on the front door," Omar Qadoos said. 

He said police held the family at gunpoint while they collected cassettes, a computer and computer discs, leaving the floor littered with clothes, papers and other items. 

Mohammed's ties to terrorism are deep. He is the uncle of convicted 1993 World Trade Center conspirator Ramzi Yousef and one of his older brothers also belongs to al-Qaida. Another brother died in Pakistan when a bomb he was making exploded. 

He also is said to be close to bin Laden's son, Saad. 

In Washington, the FBI refused to confirm Mohammed was arrested or say whether the bureau was involved. 

President Gen. Pervez Musharraf has said a small number of FBI agents are in Pakistan but only to provide intelligence on al-Qaida or Taliban fugitives from neighboring Afghanistan. 

However, Pakistani police and intelligence officials say FBI agents have been involved in nearly every important terror arrest in Pakistan. 

The Pakistani government says it has handed over more than 420 al-Qaida and Taliban suspects to the United States.

Until now, the biggest catch so far was the arrest last March of al-Qaida's suspected financier, Abu Zubaydah, who was taken into custody in a raid in the central Pakistani city of Faisalabad. Abu Zubaydah, a Saudi-born Palestinian, was said to be a link between bin Laden and many of al-Qaida's operational cells. 

Abu Zubaydah ran the Khalden camp in Afghanistan, where U.S. investigators believe many of the Sept. 11 hijackers trained. 

On Sept. 11, 2002, Ramzi Binalshibh, a would-be hijacker who could not get into the United States, was captured in the southern port city of Karachi. He was an aide to Mohammed and a key moneyman for the attacks. 

Binalshibh also was the former roommate of hijacker Mohamed Atta.