The US has yet to confirm it carried out the attack
Pakistani villagers have collected the corpses and body parts of at least 20 people killed by a reported US strike.
Intelligence officials and villagers said a pilotless drone fired a missile at a house in Mohammad Khel, North Waziristan, near the Afghan border.
The dead are said to include several suspected Arab militants.
A number of cross-border operations have been undertaken by US-led forces in Afghanistan since late August.
Pakistan says the attacks violate its sovereignty, kill civilians and anger the local population, making it harder to tackle the militants.
Pro-Taleban militants on the Pakistan side of the border are blamed for a rise in attacks on US and Nato troops in Afghanistan.
'Body parts scattered'
Pakistan's The News newspaper reported on Saturday that the strike in Mohammad Khel was carried out on the basis of information that Arab militants had been invited to a feast by pro-Taleban tribesmen following the end of Ramadan.
"We found body parts scattered all over the place in the ruins, someone's hand, someone's leg," Bakht Ali, a villager, told Reuters news agency.
An intelligence official based in the region said a woman and three children were among those killed, Reuters reported.
Pakistani army spokesman Maj Gen Athar Abbas said initial reports indicated that 20 or more people had been killed.
He said there was speculation that many were foreign militants, but added that the army was still awaiting a detailed report.
"One has to establish how many foreigners, or whether they were militants, how many civilians," the Associated Press news agency quoted him as saying.
Lt Nathan Perry, a spokesman for the US-led coalition in Afghanistan, said he had "no information to give" about the strike.