Three missiles fired by U.S. drone aircraft struck a site in Pakistan's North Waziristan region near the Afghan border on Monday, killing five, intelligence officials said.
The strike took place about 24 km (15 miles) east of Miranshah, the main town in North Waziristan.
"We have got confirmed reports of five dead but the number could be higher," said a Pakistani intelligence official in the region, who declined to be identified.
Another official said militants had cordoned off the area.
It was the second attack by pilotless U.S. aircraft in the area in the past two days. Seven people were killed in a similar strike on Saturday.
Pakistan has expressed concern that the U.S. strikes anger the public and undermine its campaign against the Pakistani Taliban.
Pakistan's have complained about pilotless drones have killed dozens of civilians officially, saying they are a violation of its sovereignty and fuel anti-U.S. feeling.
Unofficially, however, analysts say Pakistan is cooperating with the United States in identifying at least some targets the drones attack.
Separately, a pro-government cleric in the Bajaur region on the Afghan border killed after kidnapped along with three villagers on Sunday, a government official said.
The three villagers were still missing, he added.