At least 21 militants have been killed in airstrikes and a gunfight in Pakistan's restive northwestern tribal areas, officials said Sunday.

The air attacks were carried out on five insurgent hideouts in the Shawal area of North Waziristan overnight, a military statement said.

"In precise aerial strikes last night 5 terrorists hideouts were destroyed and 15 terrorists including foreigners were killed in Shawal area of North Waziristan Agency," it said.

Separately, at least six militants were killed early Sunday in a gunfight that erupted after they attacked a paramilitary checkpoint in a tribal area bordering Afghanistan, officials said.

The gunfight took place at the Ghundi checkpoint in the Khyber tribal district which is a gateway for NATO supplies to Afghanistan.

"A group of about 30 militants attacked the Ghundi checkpost early Sunday, but security forces had prior information about it and were well prepared," a senior security official told AFP on condition of anonymity.

"At least six militants were killed in the gunfight and the attacking militants were forced to flee," the official said, adding there no casualties among security forces.

The military has been fighting since June to destroy longstanding bases of the Taliban and other militants in the tribal areas.

The semi-autonomous areas have for years been a hideout for Islamist militants of all stripes -- including Al-Qaeda and the homegrown Tehreek-e-Taliban Pakistan as well as foreign fighters such as Uzbeks and Uighurs.

Washington pressed Islamabad for years to wipe out the sanctuaries, which militants have used to launch attacks on NATO forces in neighbouring Afghanistan.

More than 1,000 militants and 86 soldiers have been killed in the assault so far, according to the military. The area is off-limits to journalists, making it impossible to verify the numbers.