A security official based in neighbouring Dera Ismail Khan district - that has witnessed numerous air raids over previous months - confirmed the toll and said three Taliban members were also wounded.

The bombing follows a Taliban attack on a UN office in Islamabad on Monday.

Islamabad attack

Four Pakistanis and one Iraqi were killed at the UN's World Food Programme (WFP) building when a man disguised in military uniform walked into the lobby and detonated his explosives.

The Taliban claimed responsibility for the attack, with Azam Tariq, the spokesman, vowing more raids against local and foreign targets.

"We proudly claim responsibility for the suicide attack at the UN office in Islamabad. We will send more bombers for such attacks," he told The Associated Press news agency by telephone from an undisclosed location.

"The UN and other foreign [aid groups] are not working in the interest of Muslims. We are watching their activities. They are infidels."

Tariq said the Taliban would not attack Muslim relief groups, but that future targets would also include Pakistani security officials, government offices and American installations.

'Back broken'

Earlier Rehman Malik, the interior minister, said the Islamabad bombing was the  action of a wounded animal striking out after the military had "broken their back".

But some analysts said the attack was expected after the assassination of Baitullah Mehsud, the Pakistani Taliban leader, who was killed by a CIA drone attack in August.

Mehmood Shah, a retired brigadier and former security chief of  tribal areas, said he thought the Islamabad blasts bore the hallmarks of al-Qaeda involvement, and urged the government to prepare for more attacks.

"Al-Qaeda has jumped in to give respite to the Taliban and let them reorganise," he  said.

"We should be ready for even more deadly attacks in future because al-Qaeda is a very powerful  organisation."

Washington alleges that both Taliban and Al-Qaeda fighters are based in the mountainous tribal zone, plotting attacks on the West and slipping across the border to target foreign troops stationed in Afghanistan.