CAIRO, Egypt - Abu Laith al-Libi, a top al-Qaida commander in Afghanistan blamed for bombing a military base while Vice President Cheney was visiting last year, was killed in Pakistan by an airstrike late Monday or early Tuesday, a U.S. government official said Thursday.

The strike was conducted by a Predator unmanned drone, the official said. It was carried out against a facility in north Waziristan, the lawless tribal area bordering Afghanistan. The official spoke on condition of anonymity because he is not authorized to discuss the strike publicly.

The Predator is an unmanned aircraft developed by the U.S. CIA that can be armed with Hellfire anti-tank missiles. The CIA first used the remotely piloted reconnaissance aircraft as a strike plane in November 2002 against six alleged al-Qaida members traveling in a vehicle in Yemen.

The U.S. says al-Libi - whose name means "the Libyan" in Arabic - was likely behind the February 2007 bombing at the U.S. base at Bagram in Afghanistan during a visit by Cheney. The attack killed 23 people but Cheney was deep inside the sprawling base and was not hurt.

The bombing added to the impression that Western forces and the shaky government of President Hamid Karzai are vulnerable to assault by Taliban and al-Qaida militants.

Al-Libi also led an al-Qaida training camp and appeared in a number of al-Qaida Internet videos.

An estimated 12 people were killed in the strike, including Arabs, Turkeman from central Asia and local Taliban members, according to an intelligence official in the area who spoke on condition of anonymity. He said the bodies of those killed were badly mangled by the force of the explosion and it was difficult to identify them.

Pakistani officials denied any knowledge of al-Libi's death. The killing of such a major al-Qaida figure is likely to embarrass President Pervez Musharraf, who has repeatedly said he would not sanction U.S. military action against al-Qaida members believed to be regrouping in the lawless area near the Afghan border.

Terrorism experts said al-Libi's death was a significant setback for al-Qaida because of his extensive ties to the Taliban, but they said the terror network would likely regroup and replace him.

"Al-Libi has been waging jihad for more than 10 years and it will be a blow to both al-Qaida and the Taliban, but not in a way that will lead to the downfall of those organizations," said Eric Rosenbach, terror expert and executive director of the Center for International Affairs at Harvard's Kennedy School.

A Web site that frequently carries announcements from militant groups said al-Libi had been "martyred with a group of his brothers in the land of Muslim Pakistan" but gave no further details.

However, Pakistani intelligence officials and residents said a missile struck a compound late Monday or early Tuesday about 2 1/2 miles from the Pakistani town of Mir Ali in North Waziristan, killing 12 people, including seven Arabs as well as Pakistanis and Central Asians.

Residents said they could hear U.S. Predator drones flying in the area shortly before the explosion, which destroyed the compound.

The Pakistani newspaper Dawn said the victims were buried in a local cemetery.

Rumors spread Thursday in the border area that al-Libi or his deputy died in the missile strike. But Pakistan's Interior Ministry spokesman, Javed Iqbal Cheema, insisted authorities had "no information" indicating al-Libi was dead.

One intelligence official in the area, who spoke on condition of anonymity because of the sensitivity of the matter, said the bodies of those killed were badly mangled by the force of the explosion and it was difficult to identify them. The official estimated 12 people were killed, including Arabs, Turkomen from Central Asia and local Taliban members.

Defense Secretary Robert Gates said he did not "have anything definitive" to say on reports of al-Libi's death.

The Libyan-born al-Libi was among the most high-profile figures in al-Qaida after its leader Osama bin Laden and his deputy Ayman al-Zawahri.

In spring 2007, al-Qaida's media wing, Al-Sahab, released a video interview with a bearded man identified as al-Libi. In it, he accuses Shiite Muslims of fighting alongside American forces in Iraq, and claimed that mujahedeen would crush foreign troops in Afghanistan.

Al-Libi also led an al-Qaida training camp and appeared in a number of al-Qaida Internet videos.

He was known to maintain close ties with tribes living on the Pakistani side of the mountainous border, where U.S. officials believe al-Qaida has been regrouping.

"Al-Libi's death is a significant blow to al-Qaida the organization because he is one of the few people left in the organization who has a historical track record," said Farhana Ali, terror expert at the RAND corporation.

But, she added, "al-Qaida's strength is that it knows how to secure membership and recruitment, and because the movement will continue, al-Libi will be replaced."

A Pakistani intelligence official said that al-Libi was based near Mir Ali until late 2003 when he moved back into Afghanistan to take charge of al-Qaida operations on both sides of the border area. But he retained links with North Waziristan, the official said on condition of anonymity because of the sensitivity of the information.

Mir Ali is the second-biggest town in North Waziristan and has a strong presence of foreign militants, mostly Uzbeks with links to al-Qaida who fled to Pakistan's tribal regions after the fall of the Taliban regime in Afghanistan in 2001.

The U.S. has in the past sought to kill top al-Qaida leaders but with limited success.

Al-Zawahri, al-Qaida's second-in-command, was the target of a U.S. airstrike in Pakistan near the Afghan border on Jan. 13, 2006, but he was not at the site of the attack. Pakistan condemned the missile strike that killed at least 17 people in the village of Damadola in the Bajur tribal area, about four miles inside Pakistan.

Pakistani security officials said four top operatives were believed to be killed in that strike. The officials said the operatives included Midhat Mursi al-Sayid Umar, who the U.S. Justice Department called an explosives and poisons expert; Abu Obaidah al-Masri, the al-Qaida chief responsible for attacks on U.S. forces in eastern Afghanistan; and Abdul Rehman al-Maghribi, a Moroccan and relative of al-Zawahri, possibly his son-in-law.

Some of the officials also said a fourth man, Khalid Habib, the al-Qaida operations chief along the Afghan-Pakistan border, was believed to be dead.

Rosenbach said militants who rise to No. 3 al-Qaida positions, like al-Libi, are often in charge of planning operations, exposing them to capture or death. Others he named included Mohammed Atef, who was killed, and Abu Faraj al-Libbi, who was captured.

"It has to be one of the most dangerous jobs on earth. They generally don't last longer than a year__ mostly because the al-Qaida chief of operations has a large 'signature' resulting from planning operations," he said. "Our intelligence has done an excellent job in tracking them down."

_____

Associated Press correspondents Paul Schemm in Cairo, Fisnik Abrashi in Kabul, Zarar Khan in Islamabad and Riaz Khan in Peshawar, Pakistan and Pamela Hess in Washington contributed to this report.