A US drone aircraft fired three missiles into Pakistan's North Waziristan region on the Afghan border on Wednesday, killing at least six militants, Pakistani intelligence officials and residents said.
The strike targeted a stronghold of the Haqqani network, a major Taliban faction attacking Western forces across the border in Afghanistan. A similar strike last week in the same area killed a son of Jalaluddin Haqqani, the leader of the group.
Fire broke out after the missiles exploded in Dargi Mandi village, 4 km (2.5 miles) north of North Waziristan's main town of Miranshah.
"Thick clouds of smoke are still coming from the area," said a Reuters reporter in Miranshah.
Residents said militants had cordoned off the area and were allowing no one to approach.
Mohammad Hashim, a son of Haqqani, was killed in a strike in nearby Dandi Darpakhel village last week.
But another son of Haqqani, Sirajuddin Haqqani, is a much more high-profile target of the US drones because he has effectively taken over leadership of the militant faction from his elderly father.
US ally Pakistan officially objects to the drone strikes, saying they are a violation of its sovereignty and fuel anti-
US feeling, which complicates Pakistan's efforts against militancy.
However, at least some strikes are carried out with the consent of Islamabad, in particular those on Pakistani Taliban militants fighting the state.
The Haqqani faction does not launch attacks in Pakistan, but sends fighters across the border into Afghanistan from its stronghold in lawless North Waziristan.
Pakistan, which has been battling its indigenous Taliban in various parts of the northwest over the past 10 months, says its forces are too stretched to launch an offensive in North Waziristan, despite U.S. requests for action.
But while ruling out a major offensive against Afghan Taliban factions, Pakistani security agents have arrested at least three senior Afghan Taliban members in recent weeks, among them the Islamists' top miliary strategist, Mullah Abdul Ghani Baradar.
Visiting US General David Petraeus praised on Tuesday Pakistan's fight against the militants.
Separately, authorities found the bullet-riddled bodies of three ethnic Pashtun tribesmen killed by suspected militants in North Waziristan on suspicion of being US spies.
Meanwhile, woman and a child were killed in a landmine explosion in the Mohmand region northeast of North Waziristan, government officials aid.
In another incident, three people were killed when militants attacked a convoy of vehicles being escorted by security forces in Kurram, another ethnic Pashtun tribal region on the Afghan border, officials in the region said.