A suspected US missile strike has killed at least five people deep inside north-western Pakistan, local officials and residents say.
The strike destroyed a house near Bannu in North West Frontier Province about 50km from the Afghan border, they said.
Those killed were all local militants, officials in the area say.
In recent weeks, more than 100 people - among them suspected militants and many civilians - have died in Pakistan's tribal areas in attacks by US missiles.
There has been no official confirmation of the latest attack, which follows Pakistani government protests against a surge of air strikes by US drone aircraft targeting Islamist militants in recent months.
The BBC's Barbara Plett in Islamabad says so far these strikes have taken place in the lawless tribal areas near the Afghan border - this would be the first time a US missile has been fired so far inside Pakistani territory.
Local officials and residents said the missile was fired by an unmanned US aircraft, although one security official told the BBC it was fired from inside Afghanistan.
Until now most US air strikes have targeted militants in the tribal areas of South and North Waziristan, where the federal government does not have much of a presence.
But Bannu, which borders Waziristan, is deeper inside Pakistan and falls under the control of the regional government.
Our correspondent says the attack could, therefore, provoke more anger among Pakistani leaders, who have been denouncing the strikes as violations of national sovereignty.
They also argue that the American actions are counter-productive because civilians are killed, which deepens resentment against America and the Pakistani government.
But despite these loud and continued protests, the attacks have not stopped, leading to speculation that the two nations have a secret deal on the strikes, our correspondent says.
Elsewhere along the border, in the tribal area of Bajaur, both American and Pakistani military officers have said there is good co-operation in jointly fighting Taleban militants. There is no Pakistani military operation in progress in Waziristan.
There have been nearly 20 missile strikes in the past three months and, while US officials say al-Qaeda leaders are being successfully targeted, local tribesmen say scores of civilians have been killed.