An unmanned US drone crashed in southern Afghanistan on Sunday, while NATO forces wounded five Afghan troops in a friendly fire incident in the eastern part of the country, officials said, according to DPA. The cause of the crash of the MQ-1 Predator drone was not known, a US military statement said. "The aircraft is a medium-altitude, long-endurance, remotely piloted aircraft. The MQ-1's primary mission is conducting armed reconnaissance," the statement said, adding that the military would investigate the incident. The drones are mostly used by US-led coalition forces to attack Taliban insurgent positions in remote areas of the country. The remotely piloted planes have conducted several raids in tribal areas of neighbouring Pakistan, killing several suspected al Qaeda members allegedly stationed in areas along the Afghan-Pakistani border. Meanwhile, NATO forces wounded five Afghan army soldiers after they mistook them for insurgents in the eastern province of Kunar on Sunday, the alliance said in a statement. The Afghan army troops were on a patrol in the Pech district of the province in the vicinity of a NATO combat outpost, the statement said, adding that the NATO troops fired on "what they suspected were anti-Afghan Forces within the area."