Pakistani authorities searched Sunday for the possible wreckage of an American pilotless drone reported to have crashed in a northwestern militant stronghold, the military's top spokesman said. The CIA is believed to operate the drones, which have been used in an escalated US campaign of missile strikes against al-Qaida and Taliban targets in Pakistan's remote northwest regions bordering Afghanistan. The US rarely discusses the missile attacks and an American military spokesman in Afghanistan declined to comment on Saturday's reports of a downed drone. The reports came from Angoor Ada village in South Waziristan, a tribal region where the main Pakistani Taliban leader, Baitullah Mehsud, is based. Tribesmen, soldiers, intelligence agents and informants were hunting for possible aircraft remains in the rough terrain. We haven't found any wreckage, but we are still searching,'' Pakistan army spokesman Maj. Gen. Athar Abbas said Sunday morning. Militants are believed to use pockets of Pakistan's northwest as bases to plan attacks on US and NATO forces in Afghanistan. The missile strikes, however, prompt routine protests from Pakistani officials who say the attacks fuel anti-American sentiment. Pakistan's military has conducted offensives against insurgents in the northwest, especially the lawless tribal regions, where al-Qaida leader Osama bin Laden and his deputy Ayman al-Zawahri are rumored to be hiding. Officials recently said they had defeated the militants in Bajur tribal region and were close to victory in the adjacent Mohmand tribal area.