A Pakistani official says 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.

Friday's bombing took place in the Tirah Valley region close to the border with Afghanistan.

Political administration official Iqbal Khan says the target of the bombing was the base of the Lashkar-e-Islam group. He didn't immediately know 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 an Associated Press reporter. The commander gave his name as Mohammed.

Both groups have been fighting for control of the Tirah Valley.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

ISLAMABAD (AP) _ Pakistani intelligence officials say clashes between the military and Islamist militants have killed seven troops and 20 insurgents in a northwest region close to the border with Afghanistan.

The clashes broke out Friday in the Khyber region. The militants and the army have been battling for control there for several years in on-and-off skirmishes.

Intelligence officials say Friday's fighting was taking place in the Tirah Valley area. They spoke on condition of anonymity because they are not authorized to talk to the media.

It was not possible to independently confirm the figures because the region is off-limits to journalists.

Pakistani security forces are battling militants in several parts of the border region with Afghanistan.