A suicide bomber has killed 23 people, many of them believed to be militants, in an attack on the base of a rival insurgent group in Pakistan.
The bombing took place in the Tirah Valley region close to the border with Afghanistan.
The target of the bombing was the base of the Lashkar-e-Islam group, said an official.
It was not clear how many of those killed were militants and how many were civilians.
A commander of the Pakistani Taliban, which is a rival of Lashkar-e-Islam, claimed responsibility for the attack in a call to the Associated Press.
Both groups have been fighting for control of the Tirah Valley.
Clashes earlier in the day between Pakistani security forces and militants killed seven troops and 20 insurgents from an unknown group, officials said.
Factional fighting among the insurgents is quite common in parts of the border region, where tribal loyalties hold sway and the government has little or no control. Smuggling, kidnapping and drug production can earn commanders large sums of money.
Pakistani security forces have launched offensives in many border regions over the last four years, but have had limited success.