Pakistani officials say security forces have killed at least 33 Islamist insurgents during clashes in the North Waziristan tribal region bordering Afghanistan, while residents say many civilians were among the dead.
The fighting in North Waziristan erupted early Thursday, hours after a suicide bomber struck a major military base in the area, killing five soldiers and wounding at least 25 others.
Army officials say after the blast, a rescue effort was under way to recover wounded soldiers when a convoy came under attack in the town of Mir Ali.
The military says it killed 23 “fleeing terrorists” while three security personnel were wounded. The fighting involved artillery fire and helicopter gunships.
Officials say the military then began a major search operation that continued into Thursday and killed another 10 people described as "Uzbek militants."
Tribal sources claimed the overnight fighting also killed civilians.
It is almost impossible to verify the reports because journalists and aid workers are not allowed in the Waziristan region without special permission.
The tribal district is a known center of militancy and Taliban insurgents allegedly use it for cross-border attacks on NATO forces in Afghanistan.
The United States has long demanded Pakistan uproot these sanctuaries, saying they are fueling the Taliban insurgency.
CIA-run drones have carried out hundreds of missile strikes against in North Waziristan and killed key militant leaders but the operations have strained bilateral relations.
The Pakistani government says it lacks resources to undertake a new large-scale military operation in the area because it is already engaged in protracted counter-terrorism operations in adjoining tribal areas and elsewhere in Pakistan.