Pakistani intelligence officials say a U.S. drone strike has killed at least three suspected militants in the country's restive northwest tribal region near the Afghan border.

Authorities say the drone fired two missiles Saturday at a vehicle in North Waziristan, a known stronghold of al-Qaida and the Taliban.

The drone strike comes as Pakistani Foreign Minister Hina Rabbani Khar is visiting Washington to discuss a wide range of issues.

Drone strikes are a contentious issue between the U.S. and Pakistan. Islamabad says the strikes violate its sovereignty. The U.S. believes they are a key tool in the effort to defeat al-Qaida.