PESHAWAR, Pakistan -- A U.S. drone fired several missiles at a sprawling compound in Pakistan's northwestern tribal region bordering Afghanistan on Saturday, killing eleven militants, two Pakistani intelligence officials said.

The officials said the strike happened in Datta Khel, a town in North Waziristan, where the Pakistani military has been carrying out a major offensive against militants since last month. They said most of the slain men were members of Tehrik-e-Taliban Pakistan, an umbrella group encompassing militant organizations across the tribal areas.

The officials spoke on condition of anonymity because they are not authorized to talk to media.

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Tehrik-e-Taliban Pakistan has called for overthrowing the Pakistani government in order to implement its hard-line version of Islamic law and end cooperation with the Americans in Afghanistan.

For several years now, Washington had pushed Pakistan to take action against militant groups operating in North Waziristan.

After assuming office a year ago, Pakistan's Prime Minister Nawaz Sharif tried to resolve the issue through negotiations with the militants and urged the U.S. to refrain from drone strikes during the peace process.

But negotiations collapsed after militants attacked the country's biggest airport in the port city of Karachi on June 8, prompting the government to order military action in North Waziristan.

The start of the Pakistani offensive saw the renewal of the U.S. drone program after a roughly six-month pause.

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

Saturday's strike was the second this week. On Wednesday, a U.S. drone killed 15 militants, also in North Waziristan.

The military launched the offensive in the region on June 15, as over 800,000 people fled to other towns and cities for safety.

The military says so far it has killed nearly 500 militants and lost 26 soldiers.