A double suicide bombing in the town of Ghalalnai has killed at least 28 people.
Double suicide bombing kills 28 in Pakistan
The bombers targeted a local administration compound in Ghalalnai, the main town in the tribal district of Mohmand, about 175 kilometres (110 miles) northwest of the federal capital Islamabad and near the Afghan border.
More than 100 people were believed to have been in the compound where government officials, allied tribal elders and members of local anti-Taliban militia were holding talks, leading to fears that the death toll could rise.
"According to initial reports, 28 people died in the blasts," administration official Shamsul Islam told Pakistan's Geo television.
"There were two suicide attackers, both came on motorbikes," he added, dismissing suggestions that security had been lax.
It was the second suicide attack in five months targeting Mohmand tribal elders allied to the government. On July 9, a suicide car bomb attack killed 105 people in the region's town of Yakaghund.
"Routine security arrangements were in place. It is difficult to stop suicide bombers, they can go anywhere."
Local administration officials told AFP that the first suicide bomber blew himself up at the entrance and the second inside the compound.
"There was a meeting underway between the local administration chief and tribal elders, members of the peace committee (anti-Taliban militia) when the blast took place," another local official, Maqsood Amin, told AFP.
Amin said more than 20 people were wounded.
Mohmand is part of Pakistan's lawless northwestern tribal badlands that Washington considers a global headquarters of Al-Qaeda and a stronghold for Taliban groups fighting US-led forces in neighbouring Afghanistan.
Around 4,000 people have been killed in suicide and bomb attacks across Pakistan since government forces raided an extremist mosque in Islamabad in 2007. The attacks have been blamed on Taliban and Al-Qaeda-linked networks.
Pakistani security forces have been bogged down, fighting for years against homegrown Taliban in the tribal belt, which is semi-autonomous, and parts of the northwest that come under direct government control.
In order to assist a traditional standing army that lacks adequate equipment and counter-insurgency specialists, one of Pakistan's answers has been to arm and support tribesmen to form anti-Taliban militias in local communities.