A Pakistani security official claimed tonight that al-Qaeda's No 2 and another terror leader connected with an alleged plot to blow up transatlantic aircraft had visited a religious school on the Afghan border which was blown up in an air strike yesterday.

But the official said that neither Ayman al-Zawahri, the al-Qaeda No 2, nor the second man, named as Abu Ubaidah al-Masri, were in the madrassa when it was destroyed in the pre-dawn raid.

Some 15,000 Pashtun tribesmen demonstrated in Pakistan's North West Frontier Province today over the raid on the pre-dawn raid on the madrassa, in which 80 suspected militants were killed and which forced the Prince of Wales to cancel a visit to another madrassa in the same province.

The tribesmen, many wielding Kalashnikovs and some with rocket launchers, gathered in Khar, the main town in the semi-autonomous Bajaur tribal district, to protest against the most deadly strike launched by Pakistani forces against any militant target.

The demonstrators chanted "Down with Bush" and "Down with Musharraf" in anger at the air strike and heard from a local pro-Taleban cleric, Maulana Faqir Mohammad, who told the crowd: "Our jihad will continue and, Inshallah, people will go to Afghanistan to oust American and British forces."

The extent of US involvement in the raid is unclear, although reports in Pakistan and the United States said that the madrassa was hit by a missile from a US Predator drone warplane sent in by US forces in neighbouring Afghanistan.

Some US commentators suggested that it could have been an "October surprise" attempt to deal al-Qaeda a blow before the US midterm elections next week.

Pakistan's chief military spokesman said today that the military used intelligence used by the US-led coalition in Afghanistan but said that the military operation near Chingai village had been a Pakistani one.

Zahid Hussain, Times Correspondent in Pakistan, said that he had spoken to several eyewitnesses who had seen Predator drones circling the madrassa in the days before the attack.

"Anti-American sentiment is already very high so this is a very sensitive issue," Hussain said. "The political ramifications of this attack will be far greater than from previous attacks. I have never seen this kind of reaction."

President Pervez Musharraf said today that the building had been under surveillance for about a week and it was clearly being used for military training.

"They were militants doing military training. We were watching them for the last six or seven days - we knew exactly who they are, what they are doing," he told a security conference in Islamabad.

A remote and mountainous region, Bajaur lies across from the eastern Afghan province of Kunar, where US troops are hunting al-Qaeda leaders. It is known as a hotbed of Islamic militancy where thousands of Taleban and al-Qaeda fighters took refuge after the US-led invasion of Afghanistan in 2001.

The attack on the madrassa forced the Prince of Wales, who is making a five-day visit to Pakistan with his wife Camilla, to change his schedule and cancel a trip today to another madrassa in Peshawar, the capital of the North West Frontier Province which is 60 miles from Khar. Pakistani officials told the Prince's party that the couple's safety could not be guaranteed.

Major-General Shaukat Sultan, the chief army spokesman, denied reports that American forces took part in the attack on the madrassa.

"Intelligence-sharing was definitely there, but to say they (the coalition) have carried out the operation, that is absolutely wrong," General Sultan told the Associated Press. The AP said that the spokesman later contacted them to deny that any US intelligence was used.

The popular reaction to the attack highlights the problems faced by General Musharraf in persuading deeply conservative tribesmen to back his government against the combined forces of al-Qaeda and the Taleban. The attack forced the cancellation of a planned peace deal between the Pakistani military and local tribal leaders.

There are also fears that the protests in the North West Frontier Province could spread across Pakistan. Qazi Hussain Ahmed, Pakistan's most influential Islamist politician, was today leading a convoy of cars from Peshawar to join in the Bajaur protests. "They killed 80 teenagers who were students of the Koran," he said.

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