Dozens were injured in the blast at a council of local leaders in the Orakzai district, one of Pakistan's seven semi-autonomous tribal regions.

They were meeting to raise a militia to to evict Taleban from the region when the attack took place.

Orakzai, near the main north-west city of Peshawar, has been relatively calm.

"We were busy in raising a lashkar [tribal militia] to evict Taleban from the region when this attack took place," Qeemat Khan Orakzai, a member of the council, told Reuters news agency.

The attacker targeted a gathering of about 500 people from the Alizai tribe on Friday, according to AP news agency.

A security official told AFP news agency that the suicide attack came a day after armed tribesmen had targeted two militant hideouts.

Pro-Taleban on the Pakistan side of the border have been blamed for a rise in attacks on US and Nato troops in Afghanistan.

Pakistan's government has been courting the fiercely independent tribes to persuade them to stand up to the insurgents.

BBC