Updated

Two Pakistani intelligence officials say a suspected American drone strike has killed six militants in a northwestern tribal region where the military has launched an operation against local and foreign militants.

The intelligence officials say the strike happened Thursday morning in the town of in Datta Khel in North Waziristan, bordering Afghanistan.

The officials spoke on condition of anonymity because they were not authorized to speak to the media.

The U.S. drone strikes are a serious source of tension between Washington and Islamabad. The Pakistani government regularly denounces the strikes as a violation of the country's sovereignty.

The latest strike took place in the same region where the Pakistan army last month launched a much-awaited operation against militants, who use North Waziristan as a base to carry out attacks.