An overnight airstrike, suspected to be carried out by US forces based in Afghanistan, killed at least six Islamist militants in Pakistan's South Waziristan tribal district, officials and local residents said on Friday.
A missile believed to be fired from a pilotless Predator aircraft hit a house on Thursday night in Azam Warsak area some 15 km west of Wana, the region's main town.
"Informants have put the death toll at six," an intelligence official, who spoke on condition of anonymity, told DPA.
There were no immediate US comments on the incident.
According to him, militants in the area, a known hotbed of Al Qaeda and Taliban fighters, cordoned off the site after the blast, retrieved the bodies from the rubble and took them away to an unknown location for burial.
A religious seminary located next to the targeted house also suffered structural damages, causing injuries to a few people, a resident said without giving any numbers.
Local television channels cited unnamed sources saying the dead included foreigners, a term attributed to Al Qaeda operatives of Arab or Central Asian origin. However, the reports could not be confirmed independently.
"At this point of time, we have no shareable information about the identity of militants killed in the attack," another security official said.
The aerial raid took place hours after US Deputy Secretary of State John Negroponte met the Pakistani leadership in Islamabad to discuss regional issues, including the counter-terrorism initiatives along the Afghan frontier.
Pakistan has been angered by around three dozen US airstrikes on its tribal areas since August, and has warned that such unilateral action could undermine its efforts to fight terrorism, besides inciting anti-American sentiment among the public.
Negroponte's unannounced visit came against the backdrop of rising tensions between New Delhi and Islamabad over last month's Mumbai attacks that killed at least 173 people and injured more than 300 others.
India is blaming Pakistan-based militants from the outlawed Lashkar-e-Taiba (LeT) terrorist organisation for masterminding and executing the Mumbai siege that had strained the relations between the South Asian neighbours.
The nuclear-armed arch-rivals have reportedly put their air and naval forces on high alert but have so far refrained from relocating the land troops to the borders, a move that would place them on the verge of a full-scale conflict.
India and Pakistan have fought three wars and nearly went for a fourth one during 61 years of their independence from Britain in 1947.