It is understood 80 suspected militants have been killed in an attack by Pakistani forces on a building close to its border with Afghanistan.
Pakistani army helicopters struck a madrassa near Khar, the main town in the Bajaur area, in a region where many al-Qaeda and Taliban insurgents are thought to have sought sanctuary.
Community leaders in northwest Pakistan have rebutted claims made by army officials that those killed were members of the Taliban.
While madrassa in Pakistan have a reputation as militant recruiting grounds, the majority provide a basic education and board and lodging for children of poor families.
Local people said those killed were students and not al-Qaeda fighters.
The attack came two days after thousands of pro-militant tribesmen gathered in Bajaur in show of support for al-Qaeda and Taliban leader Mullah Omar.
Pakistan's lawless northwestern tribal areas became a sanctuary for militants who fled Afghanistan after US-led forces ousted the Taliban regime five years ago.
Pakistani forces have since launched a series of military operations throughout region in which more than 1,000 militants and 600 soldiers are reported to have died.
