The CIA-operated spy plane fired two missiles at a compound in a village in North Waziristan Agency. The attack also caused damage to a nearby mosque, residents said.
Security sources claimed that those killed in the strike belonged to Turkmenistan and had recently moved to the area. Four suspected militants were killed yesterday in a drone strike on a compound near Miranshah, the main town of North Waziristan Agency.
The back-to-back drone strikes are expected to increase tensions between the US and Pakistan, which has been calling for an end to the attacks.
The strikes came days after President Asif Ali Zardari left the NATO Summit in Chicago without announcing any move to reopen supply lines for foreign forces in Afghanistan.
Pakistan closed the routes after a cross-border NATO air raid from Afghanistan killed 24 of its soldiers in November. Since then, Islamabad has been insisting that Washington halt the drone strikes, which Pakistani leaders have described as a violation of the country's sovereignty and international law.
Islamabad has so far rejected pressure from Washington to mount a military offensive in North Waziristan agency, which US and Afghan officials have described as a safe haven for the Haqqani militant network and Taliban and al Qaeda elements.
Pakistan-US ties were further affected yesterday when a Pakistani court gave doctor Shakeel Afridi, accused of helping the CIA find Osama bin Laden, a 33-year jail term. Afridi had run a fake vaccination campaign in Abbottabad, where bin Laden was killed by US commandos last year, in a bid to gain DNA samples of the al-Qaeda leader's family.