Pakistani officials say a U.S. drone strike has killed at least 15 people in the country's northwest, in the third such attack in as many days.

Security officials say missiles hit a compound in the Hesokhel village of the North Waziristan tribal agency early Monday. There were reports that foreigners were among the dead. It was the deadliest drone strike since November of last year.

Two other suspected U.S. drone strikes hit the neighboring South Waziristan tribal district on Saturday and Sunday. Officials say Sunday's attack targeted a senior Taliban commander and killed 10 people.

The United States has ramped up its use of drones to target al-Qaida and Taliban-linked-militants in Pakistan's northwest, with eight attacks since May 23.

Washington considers drone strikes to be a vital tool in the war against al-Qaida and the Taliban.

Islamabad says the strikes are counterproductive, violate the country's sovereignty, and kill civilians.

Meanwhile, the United States and Pakistan have yet to reach an agreement on reopening NATO supply routes into Afghanistan. Pakistan shut down the supply lines after U.S. airstrikes mistakenly killed 24 Pakistani troops last November.

Pakistan's parliament has demanded a U.S. apology for the deadly cross-border attack and an end to the U.S. drone strikes.

Senior U.S. defense official Peter Lavoy is set to hold talks with Pakistani officials in Islamabad this week to try and break the deadlock over the supply routes.