Another Pakistani intelligence official confirmed the strikes and casualties but said it was not immediately clear whether any "high value target" was present in the area at the time of the attack.

in depth
  The Taliban's influence in Pakistan
  Swat: Pakistan's lost paradise
  Profile: Pakistani Taliban
  Talking to the Taliban
  Pakistan's war

The US refuses to publicly discuss its drone programme in Pakistan but drone attacks routinely target Taliban commanders in Pakistan's semi-autonomous tribal belt, which Washington calls the global headquarters of al-Qaeda.

A suspected US drone strike in Miranshah in February killed Mohammed Haqqani, a brother of al-Qaeda-linked Sirajuddin Haqqani, whose network is fighting against US and local forces in neighbouring Afghanistan.

The drone war against Taliban leaders has focused increasingly on North Waziristan, a bastion of multiple armed groups, since a December 30 suicide attack killed seven CIA employees in Afghanistan.

North Waziristan borders Khost province, where a Jordanian doctor turned al-Qaeda double agent blew himself up in the deadliest attack on the US spy agency in 26 years.

Taliban and al-Qaeda-linked groups are blamed for a wave of suicide and bomb attacks across Pakistan that have killed more than 3,000 people since 2007.

The most recent attack claimed by Pakistan's Taliban was a suicide car bombing in Lahore on Monday that killed 15 people and destroyed offices used to interrogate suspected fighters.