A bomb blast killed at least 25 people, mostly Islamist insurgents, in Pakistan's restive tribal region near the Afghan border Thursday, officials said.
More than 50 people were wounded in the explosion near a militant base in the Tirah valley of the Khyber district, a stronghold of Islamist insurgents involved in attacks on trucks carrying US and NATO supplies to Afghanistan.
The blast in remote Akkakhel village severely damaged a compound used by members of the Lashkar-e-Islam (Army of Islam), a pro-Taliban militant group with a strong presence in Khyber.
An intelligence official in the region confirmed the death toll, and said a senior leader of the Lashkar-e-Islam, Azam Khan, was among the dead.
He said the casualty count could increase as several victims were injured critically.
Earlier another official had said the bombing occurred in Orakzai district. Later on, he explained the reason for the confusion was that the site of the attack in Akkakhel village is located on the border between Khyber and Orakzai tribal districts.
Most of the casualties were moved to Orakzai, where hundreds of Taliban militants have taken refuge, fleeing a major offensive in South Waziristan.
It was not clear whether the blast was caused by a planted bomb or otherwise. However, the private Geo News television channel reported that a suicide bomber carried out the attack.
No group immediately claimed responsibility for the bombing. Security officials suspected that the attack might have been carried out by Lashkar-e-Islam's rival militant group, Ansar-ul-Islam, in revenge.
A teenage suicide bomber, believed to be linked with Lashkar-e-Islam, blew himself up at a base of Ansar-ul-Islam in Tirah on Jan 8, killing at least 10 people.