Militants ambushed a convoy of Pakistani troops in a northwestern tribal region near the Afghan border Thursday, killing seven soldiers and wounding 22, an army spokesman said.

Hundreds of soldiers backed by helicopter gunships hunted for the attackers, believed to have fled to a village near the site of the ambush on the outskirts of Miran Shah, the main town in North Waziristan, security officials said.

At least five suspected militants were killed in the fighting, said one official, who requested anonymity because he wasn't authorized to speak to journalists.

An Associated Press reporter heard artillery fire and gunshots, but troops mounted a roadblock, preventing journalists from reaching the scene of the fighting.

Army spokesman Maj. Gen.Shaukat Sultan said seven troops were killed and 22 wounded in the militant attack on three vehicles. The injured troops were transported to a hospital. At least three were in critical condition, said the security official who spoke on condition of anonymity.

Militants also attacked a military post with rockets near Miran Shah late Wednesday, triggering a shootout, but no security forces were hurt. It was not clear whether there were any militant casualties.

Pakistan is a key U.S. ally in its campaign against terrorism, and North Waziristan and nearby tribal areas have been the scene of scores of military operations against remnants of the Taliban, Usama bin Laden's Al Qaeda network and their local supporters.

Pakistan has deployed about 80,000 troops to the border region, and hundreds of militants and soldiers have been killed in fighting.

On April 12, the military killed seven terror suspects near the site of Thursday's attack. Senior officials said the dead including Egyptian Mohsin Musa Matawalli Atwah, who was on the FBI's list of most-wanted terrorists for alleged involvement in 1998 bombings of U.S. embassies in Tanzania and Kenya.