Pakistan’s military said Wednesday it killed 40 insurgents and destroyed five of their hideouts in fresh air attacks as part of a major offensive against the Taliban in the northwest.

Pakistan's military said Wednesday it killed 40 insurgents and destroyed five of their hideouts in fresh air attacks as part of a major offensive against the Taliban in the northwest.

Pakistan began the long-awaited push to clear the bases from North Waziristan district, on the Afghan border, in June after a bloody attack on Karachi airport finally sank faltering peace talks with the rebels.

A military statement said that "in precise aerial strikes" five hideouts and ammunition dumps were destroyed and forty insurgents including foreigners were killed in the villages of Nawe Kili and Zaram Asar, north of Dattakhel in North Waziristan.

The conflict zone is off-limits to journalists, so there is no way to independently verify the number and identity of those killed.

The Pakistani foreign ministry Wednesday said that it had lodged a "strong protest" with Afghanistan after militants launched an attack on Pakistani troops from Afghan side of the border in North Waziristan on Tuesday, in which four Pakistani soldiers were killed.

"Between 90-100 terrorists entered Pakistan territory on 16 September 2014 from recently established sanctuaries/safe havens across the border in Khost, Afghanistan, opposite North Waziristan," it said.

"The attack was successfully repulsed by the Pakistan Military troops inflicting casualties upon the terrorists who fled back to Afghanistan leaving behind three dead bodies," the ministry said.

Pakistan also conveyed its "serious concern" to Afghan authorities over the recently established militant sanctuaries in Khost and Paktika provinces of Afghanistan, it added.

Air strikes, artillery, mortars and ground troops have all been used to retake territory in North Waziristan, which had become a haven for fighters with the Tehreek-e-Taliban Pakistan (TTP) and other militant outfits.

The semi-autonomous tribal areas on the Afghan border have for years been a hideout for militants of all stripes -- including Al-Qaeda and the homegrown TTP as well as foreign fighters such as Uzbeks and Uighurs.

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