Pakistan's army said Wednesday it was probing the crash of a suspected unmanned US spy plane in a tribal area bordering Afghanistan where American military strikes have caused tensions. The aircraft crashed on Tuesday night in the South Waziristan region, a known haunt of Al-Qaeda and Taliban militants. The army said it appeared to have malfunctioned, but residents said it may have been shot down. "A surveillance unmanned aerial vehicle (UAV), while flying over the Pak-Afghan border yesterday night, crash landed on this side of the border... apparently due to malfunctioning," a Pakistani military spokesman said. "The wreckage of the UAV has been recovered from the site by the security forces personnel and the matter is under detailed investigation," the spokesman said in a statement. It did not say who the drone belonged to but security officials said it was an American aircraft. The Pentagon said it had no report of any crash, while the CIA declined to comment. "We have no reports of any loss of DoD (Department of Defense) drones," said Lieutenant Colonel Mark Wright. Pakistani officials earlier said ethnic Pashtun tribesmen in Jalal, a village close in South Waziristan, had picked up the drone but that troops then retreived it. "No firing was heard in the area so there is no question of it being shot down," a senior security official said on condition of anonymity. Residents however said that the plane was indeed brought down by fire. "The tribesmen fired at the drone and it fell out of the sky," one resident said by telephone, asking not to be named for fear of reprisals.