Four missiles hit the house of a local tribesman in Shaktoi, South Waziristan, near the Afghan border, an official told the BBC.

The official said all those killed in the attack were militants.

Last week an attack in the same area reportedly targeted Pakistani Taliban leader Hakimullah Mehsud, but the Taliban say he survived.

"Now the death toll is 15. It could rise further. People are still busy removing rubble," a senior security official told Reuters.

Most of the casualties were foreign fighters, he added.

Another report said the house was being used by Uzbek militants fighting with the Taliban.

Hakimullah Mehsud has led the Pakistani Taliban since former leader Baitullah Mehsud was killed in a drone attack last summer.

The US has stepped up drone attacks in north-west Pakistan since a suicide bomber killed seven CIA agents across the border in Afghanistan last month.