Pakistan's military on Friday said it killed 15 insurgents in air strikes in a restive tribal district near the Afghan border, a region where it has been battling Islamist groups for more than a decade.

"Three terrorist hideouts were destroyed and 15 terrorists were killed in effective and precise aerial strikes early Friday morning in Khyber", where the Taliban and another banned militant group, Lashkar-e-Islam, have taken refuge, the military said in a statement.

Pakistan has been battling Islamist groups in its semi-autonomous tribal belt since 2004 after its army entered the region to search for Al-Qaeda fighters that had fled across the border following the US-led invasion of Afghanistan.

In June, the army began an operation in the North Waziristan district after a bloody raid on Karachi Airport ended faltering peace talks that began earlier in the year.

North Waziristan had become a major base for the Tehreek-e-Taliban Pakistan (Pakistani Taliban), which rose up against the state in 2007.

The United States has long called for action in the area because militant groups there have targeted NATO forces in neighbouring Afghanistan.

Pakistan's army says it has killed more than a thousand militants and lost 86 soldiers since the start of the operation.

But the toll and identity of those killed is impossible to verify because journalists do not have regular access to the conflict zones. Critics charge that many of the dead were non-combatants.