Pakistani officials say a suspected U.S. drone strike has killed at least four militants in Pakistan's northwestern tribal region, near the Afghan border.

Authorities say the drone fired at least four missiles into a vehicle Sunday near the town of Datta Khel in the North Waziristan region.

U.S. officials have never publicly acknowledged the use of drone strikes inside Pakistan, but privately they have confirmed their existence to various news outlets. Pakistan has condemned the attacks as a violation of its sovereignty, but the strikes are believed to be carried out with the help of Pakistani intelligence.