Pakistani intelligence officials say three US missile attacks spaced just hours apart have killed at least 18 people in the country's northwest.

At least nine people were killed in the first attack, when missiles struck a vehicle and compound in the Mandi Khel area of the North Waziristan tribal region, officials said.

Two hours later, drones struck the same site again, killing at least five people who had gathered to retrieve the bodies.

The men killed in the first two attacks are thought to have been connected to Taliban commander Hafiz Gul Bahadur, officials in Peshawar and Miranshah told the AFP news agency.

A third raid on Saturday targeted a moving vehicle, killing four people in the Mohammed Khel area of North Waziristan, the intelligence officials said.

The identities and nationalities of the people killed were not immediately known, officials said.

"We have received such reports that four foreigners were also killed in these fresh attacks but their identities are still not known, and we are collecting more information," an official said.

The officials spoke on condition of anonymity as they are not authorised to speak to the press.

The attacks came a day after four missiles struck a convoy, killing eight suspected fighters belonging to the Haqqani group.

Up to 35 people were believed to have been killed in similar attacks on Monday and Tuesday.

The US does not confirm drone attacks but its military and the CIA operating in Afghanistan are the only forces that deploy the unmanned aircraft in the region.