Tribesmen gather near the bodies of those killed during a Pakistan army air strike in Chenagai, 10 km (six miles) north of Khar, the main town in the Bajaur tribal region bordering Afghanistan October 30, 2006. [Reuters]

ISLAMABAD, Pakistan - Pakistani helicopter gunships on Monday destroyed a religious school the military said was fronting as an al-Qaida training camp, killing 80 people in the country's deadliest military operation targeting suspected terrorists.

Islamic leaders and al-Qaida-linked militants blamed the United States for the airstrike and called for nationwide demonstrations to condemn the attack that flattened the school -- known as a madrassa -- and ripped apart those inside. Furious villagers and religious leaders said the pre-dawn missile barrage killed innocent students and teachers.

US and Pakistani military officials denied American involvement.

Among those killed in the attack in the remote northwestern village of Chingai, two miles from the Afghan border, was a cleric who had sheltered militants in the past and was believed associated with al-Qaida's No. 2 leader, Ayman al-Zawahri.

The raid threatens efforts by President Gen. Pervez Musharraf to persuade deeply conservative tribespeople to back his government over pro-Taliban and al-Qaida fighters, who enjoy strong support in many semiautonomous regions in northern Pakistan. The planned signing of a peace deal between tribal leaders and the military was canceled Monday in response to the airstrike.

Musharraf has been under intense pressure, particularly from the United States and Afghanistan, to rein in militant groups, particularly along the porous Pakistan-Afghan frontier, where Osama bin Laden and al-Zawahri are believed to be hiding. The Pakistani leader, along with Afghan President Hamid Karzai, met with President Bush in Washington last month to address the issue.

Protests were held from the northwestern city of Peshawar to the southern city of Karachi, the largest taking place in Chingai and the Bajur district's main town of Khar, where 2,000 tribesmen and shopkeepers chanted "Death to Musharraf! Death to Bush!"

Amid fears of unrest, Britain's Prince Charles, who arrived in Pakistan on Sunday for a five-day stay, canceled a visit planned for Tuesday to Peshawar.

The raid was launched after the madrassa's leaders, headed by cleric Liaquat Hussain, rejected government warnings to stop using the school as a training camp for terrorists, said army spokesman Maj. Gen. Shaukat Sultan.

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

Militant groups in Bajur are believed to ferry fighters, weapons and supplies to Afghanistan to target US forces there and Pakistani soldiers on this side of the ethnic-Pashtun majority tribal belt.

Sultan said 80 people were killed in the building, which was 100 yards from the nearest house. Local political officials and Islamic leaders corroborated the death toll.

Sultan denied reports that al-Zawahri was in the area at the time of the attack. "It is all wrong, speculative and we launched this operation on our own to target a training facility," he said. A Bajur-area intelligence official said word was spreading among residents that al-Zawahri may have been expected at the madrassa, but he said the reports were wrong.

Hussain, the cleric believed to have been a deputy of al-Zawahri, was among those killed, the intelligence official and residents said.

Another al-Zawahri lieutenant, Faqir Mohammed, apparently left the madrassa 30 minutes before the strike, according to the official, who spoke on condition of anonymity as he was not authorized to speak to the media.

Hours later, Mohammed addressed 10,000 mourners at a funeral for some of the victims.

"We were peaceful, but the government attacked and killed our innocent people on orders from America," said Mohammed, who was surrounded by dozens of militants brandishing semiautomatic weapons. "It is an open aggression."

Three funerals were held one after the other in a field near the madrassa, where the remains of at least 50 people were laid on wooden beds placed side by side in rows and covered with colored blankets.

Villagers walked among the beds and offered prayers. One man strode through the crowd holding aloft -- trophy-style -- a severed, blackened hand. Militants, their faces covered with brown and red scarves, patrolled the crowd.

On Saturday, Mohammed led a nearby rally of 5,000 pro-Taliban and al-Qaida militants where he denounced the Pakistani and US governments and praised bin Laden.

Fears are high that the attack will fan unrest across Pakistan, which witnessed violent protests this year after European newspapers published cartoons of Islam's Prophet Muhammad, as well as the August killing of a ethnic-Baluch tribal chief in another Pakistani military raid.

In Islamabad, Pakistan's most influential Islamist political leader blamed American forces for the attack, without providing evidence to support his claim, and called for protests Tuesday.

"It was an American plane behind the attack and Pakistan is taking responsibility because they know there would be a civil war if the American responsibility was known," said Qazi Hussain Ahmed, leader of a six-party religious alliance opposed to Musharraf.

Ahmed claimed that 30 children were among Monday's dead. But Sultan, the army spokesman, said no children or women were killed and rejected suggestions of US or NATO involvement. Most victims' bodies were so mangled that positive identification was impossible.

The US military also denied involvement.

"It was completely done by the Pakistani military," US military spokesman Maj. Matt Hackathorn said in Afghanistan.

The attack happened about two miles from Damadola, where in January a US Predator drone aircraft fired a missile that purportedly targeted -- and missed -- al-Zawahri, but killed several al-Qaida members and civilians instead.

Thousands of tribespeople traveled from nearby villages to inspect Chingai's destroyed madrassa, many wailing and others chanting "Long live Islam." The blast leveled the building, tearing mattresses and scattering Islamic books, including copies of the Quran.

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