ISLAMABAD, Pakistan — A senior al-Qaida leader, described by U.S. counterterrorism officials as the group's No. 3 man and a close confidant of Osama bin Laden, has been arrested after a firefight in northwestern Pakistan, officials said today.

In Washington, President Bush said the capture of Abu Farraj al-Libbi "represents a critical victory in the war on terror," and he praised the Pakistani government and President Gen. Pervez Musharraf for the arrest.

"Al-Libbi was a top general for bin Laden," Bush said. "He was a major facilitator and a chief planner for the al-Qaida network. His arrest removes a dangerous enemy who is a direct threat to America and for those who love freedom."

Bush added, "We'll stay on the offensive until al-Qaida is defeated."

Al-Libbi, who allegedly orchestrated two assassination attempts against Musharraf, was arrested after a firefight on the outskirts of Mardan, 30 miles north of Peshawar, capital of the deeply conservative North West Frontier Province, the government and security officials said.

Al-Libbi, a native of Libya, was arrested earlier this week, Information Minister Sheikh Rashid Ahmed told The Associated Press.

"This is a very important day for us," Ahmed said. "This arrest gives us a lot of tips, and I can only say that our security agencies are on the right track" in the hunt for bin Laden, Ahmed said.

"This man knew many people and many hideouts."

A U.S. counterterrorism official, speaking on condition of anonymity, said al-Libby was the No. 3 al-Qaida figure behind bin Laden and his deputy, Ayman al-Zawahri. Al-Libbi assumed more authority within al-Qaida after the March 2003 arrest of Khalid Shaikh Mohammed, the official said, adding that al-Libbi is believed responsible for planning attacks around the world, including in the United States.

The official said the relationship between bin Laden and al-Libbi predates the formation of al-Qaida in the 1990s.

Interior Minister Aftab Khan Sherpao described al-Libbi as an "al-Qaida planner" who held a senior place in the terror group's hierarchy. He said the U.S. government was offering a $10 million bounty for information leading to al-Libbi's arrest, though he does not appear to be on the FBI's list of the globe's most-wanted terrorists.

Neither minister would provide details on where al-Libbi was captured or where he was being held.

But three Pakistani intelligence officials told AP on condition of anonymity that al-Libbi was one of two foreigners arrested Monday after a firefight on the outskirts of Mardan.

One of the officials said 11 more terror suspects — including three Uzbeks, an Afghan and seven Pakistanis — were arrests before dawn today in the Bajor tribal region. The official would not say what prompted authorities to launch the raid or whether it was linked to al-Libbi's capture.

The intelligence officials said authorities were led to al-Libbi's hideout by a tip that foreigners had been spotted in the area. The suspect was held overnight at a military facility in Mardan, then transferred by helicopter to the capital, Islamabad, the officials said.

Sherpao would not speculate on whether the arrest might help lead to the capture of bin Laden or al-Zawahri, who have eluded a 3 1/2-year dragnet since the Sept. 11 attacks. Mohammed was handed over to U.S. custody, and his whereabouts are unknown.

"We have no information" about the al-Qaida leaders, he said. "It's premature to say (whether al-Libbi's arrest will help track them down), but definitely interrogation is going to take place."

Al-Libbi reportedly spent time in South Waziristan, a tribal region along the border with Afghanistan that is considered a likely hideout for bin Laden. But he fled following a series of military operations in the area last year. Authorities had said privately in recent weeks that they believed they were zeroing in on his location.

Before Ahmed's announcement, senior government and military officials repeatedly denied rumors they had al-Libbi in custody.

Al-Libbi is accused of masterminding two bombings against Musharraf in December 2003. The military leader escaped injury but 17 others were killed in one of the attacks.

Sherpao said it was too early to comment on whether al-Libbi might be turned over to the United States, but he stressed there were important cases pending against him in Pakistan.

Musharraf, a key ally in the U.S.-led war on terrorism, named the Libyan as the chief suspect in the bombings against him. He was among six suspects identified as Pakistan's most-wanted terrorists in a poster campaign last year.

A photograph of al-Libbi released by the government today and taken after his arrest shows a disheveled, bearded man with sunken eyes and what appears to be a skin condition.

It is in striking contrast with the poster photo, in which al-Libbi looks healthy and is dressed in a Western-style suit and tie.

The other suspects were all Pakistanis linked to Lashkar-e-Jhangvi, a Sunni Muslim militant group believed tied to al-Qaida. Al-Libbi is not on the FBI's list of the globe's most-wanted terrorists.

One of the suspects, Amjad Hussain Farooqi, was killed in a shootout with security forces in southern Pakistan in September.

Farooqi, a senior member of Lashkar-e-Jhangvi, was accused of plotting the bombings against Musharraf with al-Libbi and of involvement in the kidnapping and beheading of Wall Street Journal reporter Daniel Pearl in Karachi in 2002.

Pakistan has arrested hundreds of terror suspects since Musharraf ended the country's support of the Taliban regime in neighboring Afghanistan after the Sept. 11 attacks on America and waged bloody operations against al-Qaida-linked militants along the Afghan border.

It has handed over about 700 al-Qaida suspects to the United States, including Mohammed, Sept. 11 planner Ramzi Binalshibh and al-Qaida senior operative Abu Zubaydah.