At least seven people have been killed in a missile strike in north-west Pakistan, security officials say.
Unconfirmed reports said a US drone fired four missiles at a compound in North Waziristan and two cars parked outside were destroyed.
In a separate development, a key border crossing used by Nato to move supplies into Afghanistan has been reopened.
The border had been shut when two Pakistani soldiers were killed in a US helicopter strike.
The closure of the Torkham crossing prompted the Taliban in Pakistan to launch a series of raids on stranded Nato convoys.
The Pakistani government agreed to re-open the border on Saturday, following a US apology for its soldiers' deaths.
Al-Qaeda European 'plot'
The latest drone strike came as the US military stepped up its attacks on militant targets in the tribal areas near the Afghan border.
The upsurge is reportedly intended partially to halt an alleged al-Qaeda plot to attack European cities. Earlier this month, five German nationals died in a drone strike linked to the plot.
Sunday's drone attack was said to have first attacked a camp housing Afghan refugees close to the town of Mir Ali, destroying a house and two cars.
Minutes later, two people were killed in a missile attack close to a river bank outside the camp, Associated Press reports.
Although the target of the raid is not clear, the area is said to be dominated by a militant group that regularly attacks troops with the Nato-led force in Afghanistan.