The sources said a US drone fired at least two missiles which hit a flying coach at Machikhel area, some eight kilometres in northwest from tehsil Mirali. They said the vehicle was coming from Mirali Bazaar to Machikhel area and was carrying seven persons, all dead in the strike. The official sources confirmed the incident.
Another source said the identity of those killed in the attack was yet to confirm.
It was the eighth drone attack on tribal areas since the killing of al-Qaeda chief Osama bin Laden by US commandos in a raid in Abbottabad on May 2.
Agencies add: A US drone fired two missiles which hit a vehicle. At least seven militants have been killed, one security official in Peshawar told AFP.
Another intelligence official in Miranshah said two drones fired four missiles, hitting a van and killing at least seven militants.
I do not know whether there was a high-value target. We received reports that those killed in the flying coach were all foreigners, he said.
The drone strikes are hugely unpopular among the general public and inflame anti-US feeling, which has heightened further after the bin Laden raid.
Missile attacks doubled in the area last year, with more than 100 drone strikes killing over 670 people in 2010, compared with 45 strikes that killed 420 in 2009, according to an AFP tally.
Most have been concentrated in North Waziristan, where the United States wants the Pakistan military to launch a ground offensive as soon as possible.
Pakistan says its troops are too overstretched to mount such an assault and that any campaign will be of its own time and choosing.
The United States does not confirm drone attacks, but its military and the CIA in Afghanistan are the only forces that deploy them in the region.
The parliament has called for an end to US drone strikes and said there must be no repeat of the operation that killed bin Laden.