A US drone attack on Friday killed four people in Pakistan's north-western region, along the Afghan border, security officials said, DPA reported.
The unmanned aircraft fired two missiles into a car and a house in the Khaisoor area of North Waziristan, one of the seven tribal districts where the Taliban and al-Qaeda have hideouts.
"The locals have pulled out the charred bodies of all four people in the vehicle, while the debris of the demolished house is being combed to find dead or injured, if there are any," said an intelligence official who spoke on condition of anonymity.
The identity of those killed was not yet known.
The attack was part of a US drone campaign that has intensified since US President Barack Obama took office in 2009. The main targets since last year have been Taliban and al-Qaeda bases in North Waziristan.
Washington is pressing Pakistan for military action in North Waziristan - a hub of the radical Islamist Haqqani network, alleged to be responsible for high-profile attacks on NATO and Afghan forces, particularly in the Afghan capital Kabul.
But Pakistan says its forces are overstretched by operations against Islamist insurgents in other parts of the region.
Washington has suggested that Islamabad is playing a double game as a key ally in the fight against terrorism while helping the Taliban fight international forces in Afghanistan.
Admiral Mike Mullen, the chairman of the US Joint Chiefs of Staff, on Thursday accused Pakistan's spy agency, the Inter-Services Intelligence agency (ISI), of supporting the Haqqani network.
"With ISI support, the Haqqani operatives planned and conducted that (September 10) truck bomb attack (on a NATO base), as well as the assault on our embassy. We also have credible intelligence that they were behind the June 28th attack on the Intercontinental Hotel in Kabul and a host of other smaller, but effective operations," Mullen said.
The statement sparked a strong reaction from Pakistan, whose Foreign Minister Hinna Rabbani Khar warned that the US could lose an ally.
Pakistani military chief general Ashfaq Parvez Kayani on Friday termed the allegations "very unfortunate and not based on facts."
"Admiral Mullen knows fully well which countries are in contact with the Haqqanis. Singling out Pakistan is neither fair nor productive," said Kayani, in an apparent reference to reports that the US had established contacts with the Haqqani group, seeking negotiations.
The relationship between Washington and Islamabad has been particularly strained since the US raid that killed al-Qaeda leader Osama bin Laden on Pakistani soil in May.