At least 20 people were killed yesterday when US missiles struck an Islamic school founded by a friend of Osama bin Laden in Pakistan's lawless tribal region near the Afghan border.

The attack by unmanned American drone aircraft was the third aimed at militant leaders and their hideouts just inside Pakistani territory. Officials and residents of the village of Dande Darba Khel in North Waziristan said that two drones fired three missiles, which also hit houses close to the Islamic seminary, killing three women and two children.

The madrassa, founded by Jalal-uddin Haqqani, a veteran Afghan commander and old associate of bin Laden, was closed by Pakistani forces in 2002 but several members of Mr Haqqani's cabal were believed still to be living in the area.

Uzbek and Arab fighters were believed to have taken sanctuary in the village and several foreign militants were reported to have been killed in yesterday's strike. A missile struck a house owned by the Haqqani family, killing his sister, sister-in-law and two nieces, residents said.

Major-General Athar Abbas, the chief Pakistani military spokesman, said the attack was being investigated.

Mr Haqqani, who has been suffering from poor health, is less active but his eldest son Sirajuddin is leading Taleban insurgents fighting the US-led coalition forces in the neighbouring Afghan provinces of Khost and Paktia. Both men were reported to be in Afghanistan at the time.

Mr Sirajuddin has been accused by the US and Afghan governments of masterminding a suicide bomb attack on the Indian Embassy in Kabul in July that killed about 60 people, including a senior Indian diplomat.

The surge of US strikes inside Pakistan has provoked intense reaction in the country, which is a close US ally in the War on Terror, adding to the problems for Asif Ali Zardari, who is due to take over as Pakistan's new President today. Mr Zardari, 53, the widower of Benazir Bhutto, who is to replace Pervez Musharraf, won an election at the weekend with an overwhelming majority.

The new President has vowed to continue Pakistan's support for the West and intensify the campaign against Islamic militants who control the tribal region near the Afghan border as well as a large part of North West Frontier Province. The US attacks have placed the new civilian Government under tremendous pressure and triggered militant attacks against Pakistani security forces.

US official forces carried out a ground assault in South Waziristan last week, the first known incursion into Pakistan by US troops since the 2001 invasion of Afghanistan. More than 20 people, including women and children, were killed. Another five people died a day later in a US drone missile strike in North Waziristan.

Speculation that the US strikes were approved by Pakistan's new Government have been denied by Pakistani civil and military officials.

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