At least six people have been killed in a missile strike in the Pakistani tribal area of South Waziristan, near the Afghan border, officials have said.
The missile, reportedly fired from Afghanistan, hit a house next to a mosque in the village of Azam Warsak.
A Pakistani security official said it was not clear if the missile had been launched by Taleban fighters or Nato-led forces fighting them.
Pakistan has protested at recent Nato strikes in which civilians were killed.
Local residents told a news agency that the missile struck a house belonging to a local tribesman and suspected fighters used to stay there.
Other villagers said they had heard jets coming from Afghanistan before the strike.
Earlier this month, Nato-led forces in Afghanistan said they fired into Pakistan after coming under attack from there by suspected militants.
Nato said it had closely coordinated with Pakistan's military, who agreed to help if firing from Pakistan continued.
Nato has rejected reports of a build-up of international forces on the Afghan side of the border.
In recent months the US and its allies have pledged hundreds of millions of dollars in military and other forms of assistance to help Pakistan's new government tackle militancy in border tribal areas.
Earlier this month, US Secretary of Defence Robert Gates said he was considering sending additional troops to Afghanistan to counter the flow of fighters from Pakistan.
The move is in response to growing US frustration with what it sees as Pakistan's lack of action against the pro-Taleban fighters operating along the border with Afghanistan.
PHOTO CAPTION
Map of Pakistan
BBC