Pakistani intelligence officials say a U.S. missile strike near the Afghan border has killed 20 people.

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A U.S. MQ-1B Predator takes off from Balad Air Base in Iraq. ((Senior Airman Julianne Showalter/U.S. Air Force/File/Reuters))

The strike Wednesday occurred in the Shawal area of North Waziristan, a tribal region home to several militant groups involved in attacks on NATO forces across the border in Afghanistan.  

The two intelligence officials spoke on condition of anonymity because they are not authorized to brief the media.

The U.S. relies heavily on the drone-fired missiles to take out al-Qaeda and Taliban targets in Pakistan. 

Islamabad officially protests the strikes as violations of Pakistan's sovereignty, but it is widely believed to have secretly provided intelligence for some of them.