Pakistani troops and helicopters firing missiles killed as many as 80 militants training at a religious school used as an al-Qaeda training centre near the Afghan border, officials said.

Local leaders said all those slain when the school, or madrassa, was destroyed were civilians.

Army spokesman Maj. Gen. Shaukat Sultan said initial estimates based on intelligence sources on the ground indicated that the attack killed about 80 suspected militants, who appeared to be in their 20s and were from Pakistan and other countries.

"These militants were involved in actions inside Pakistan and probably in Afghanistan," Sultan told the Associated Press.

The bodies of 20 men killed in the attack were lined up in a field near the madrassa, in Chingai village near Khar, the main town in the Bajur tribal district, before an impromptu burial attended by thousands of local people, according to an Associated Press reporter at the scene.

Search for survivors

Dozens of villagers sifted through the rubble of the madrassa, shifting blocks of smashed concrete and mud bricks aside to try to find survivors. Some picked up body parts scattered across the area and placed them in plastic bags normally used for fertilizer.

"We heard helicopters flying in and then heard bombs," said one of the villagers, Haji Youssef. "We were all saddened by what we have seen."

Among the dead was Liaquat Hussain, a local Islamic cleric who ran the madrassa, locals said. Several of his aides also died, they said.

The attack came two days after 5,000 pro-Taliban tribesmen held an anti-American rally in the Bajur area near Damadola, a village close to the site of an alleged U.S. missile attack that killed several al-Qaeda members and civilians in January.

"We received confirmed intelligence reports that 70-80 militants were hiding in a madrassa used as a terrorist-training facility, which was destroyed by an army strike, led by helicopters," Sultan said.

An Associated Press reporter living in the area said he saw several helicopters hovering near his house early Monday before hearing a series of explosions, apparently caused by missiles being fired into the madrassa compound.

Helicopters fired four to five missiles into the madrassa, Sultan said.

Attack 'very strange'

The strike came on the day Bajur tribal leaders and the military were expected to sign a peace deal, similar to an accord signed earlier this year in nearby North Waziristan.

"This attack is very strange as we were told Sunday that the peace agreement would be signed today," local lawmaker Mohammed Sadiq said.

Sultan declined to say if an accord was scheduled to be signed Monday, but added that militants cannot hide behind peace deals. He said the purported militants using the madrassa had rejected orders to end their activities.

A senior intelligence official in Bajur also said a local al-Qaeda leader, Faqir Mohammed, who led Saturday's rally, was believed to have been inside the madrassa.

It was unclear if Mohammed was among those killed, said the official, who declined to be identified further because he was not authorized to speak to the media.

Siraj ul-Haq, a cabinet minister from the North West Frontier Province, condemned the attack and announced he would resign from the government in protest.

"The government has launched an attack during the night, which is against Islam and the traditions of the area," ul-Haq told the AP during the funeral. "They [the victims] were not given any warning. This was an unprovoked attack on a madrassa. They were innocent people."

Protests planned

Ul-Haq, who belongs to the powerful Islamic political party, Jamaat-e-Islami, said protests would be staged throughout the northern tribal region on Tuesday to denounce the attack.

Pakistan has been trying to defeat militants along its porous border with Afghanistan since the U.S.-led invasion of that country in 2001 fanned increased terrorist activity on the Pakistan side of the frontier.

Pakistan became a key U.S. ally in its war on terror after the Sept. 11 attacks in the U.S., and has deployed about 80,000 soldiers to flush out Taliban and al-Qaeda members hiding in the mountainous frontier tribal region.

Al-Qaeda leader Osama bin Laden and his deputy, Ayman al-Zawahri, are believed to be hiding along the Pakistan-Afghan border.