Pakistan summons U.S. envoy over airstrikes

ISLAMABAD, Pakistan (CNN) -- Pakistan's foreign ministry said Wednesday that it has lodged a "strong" protest with the U.S. ambassador over missile attacks conducted on Pakistani soil by unmanned drones.

The ministry said it summoned Ambassador Anne Patterson to underscore that such attacks violate Pakistan's sovereignty and should be stopped immediately.

A statement from the ministry said Patterson was also told that the attacks have cost lives and undermined public support for Pakistan's counter terrorism efforts.

The ministry lodged its protests three days after a missile strike from a suspected U.S. drone on a compound in South Waziristan killed 20 people.

Pakistan has repeatedly raised objections to foreign nations violating its sovereignty to pursue terrorists. A U.S. ground operation in September that left several civilians dead rankled relations between the two countries.

Last week, Pakistan's parliament passed a resolution that condemned any incursion on Pakistani soil by foreign forces.

The resolution called for a review of the country's national security strategy and said the government needs to safeguard its sovereignty and territorial integrity.

The ministry said it handed Patterson a copy of the resolution.

The U.S. and NATO, which have troops in Afghanistan, have been seeking a way to effectively battle militants who launch attacks from Pakistan's swath of tribal areas along the border.

They have become frustrated with Islamabad over the years, saying it is not being proactive enough against militants -- a claim Pakistan denies.

The United States is the only country operating in the region known to have the capability to launch missiles from drones, which are controlled remotely.

In another development, suspected Taliban militants kidnapped three government officials from an administrative office in Pakistan's tribal region Wednesday, officials said.

The militants abducted two employees and a security guard from the Ambar district in Mohmand Agency.

Mohmand is in the Federally Administered Tribal Areas, where U.S. and Pakistani officials have reported a presence of militants.

Earlier in the day, militants tried unsuccessfully to take control of a school in Mohmand and abduct about 100 students, authorities said. A shootout with Frontier Corps followed, in which one militant was killed and another arrested.

The Frontier Corps is a paramilitary force which uses recruits from Pakistan's tribal areas and is overseen by Pakistani army officers.

Also Wednesday, a suicide car bomber detonated explosives outside a police checkpoint in northwest Pakistan, killing two security personnel, officials said.

The Wednesday afternoon attack in the Bannu district of the North West Frontier Province also wounded a dozen people, military sources said.

The bomber targeted a check point near a military hospital, said the sources who did not want their names revealed because they are not authorized to speak to the media.

CNN's Reza Sayah and journalist Janullah Hashimzada contributed to this report