Pakistan's military Tuesday said it had killed 28 militants in air strikes in the restive tribal region near the Afghan border, a region where it has been battling Islamist groups for more than a decade.

The strikes, that also killed a number of foreign fighters, took place on Tuesday in Dattakhel area of North Waziristan district, a stronghold of Taliban-linked groups, 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 agency after a bloody raid on Karachi Airport ended faltering peace talks between the government and militants.

North Waziristan is a major base for the Tehreek-e-Taliban Pakistan (Pakistani Taliban), which began it's campaign against the state in 2007 and also provides shelter to a number of foreign militant groups.

The United States has long called for action against militant groups in North Waziristan who have used the area as a staging post for attacks against 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 difficult to verify because journalists do not have regular access to the conflict zones.

Critics charge that many of the dead were non-combatants.

In July, an air strike in North Waziristan district that the military said killed 35 militants in fact claimed the lives of 37 civilians, according to multiple accounts by residents.