The US Air Force on Tuesday confirmed for the first time that it is flying a stealth unmanned aircraft known as the "Beast of Kandahar," a drone spotted in photos and shrouded in secrecy.

The RQ-170 Sentinel is being developed by Lockheed Martin and is designed "to provide reconnaissance and surveillance support to forward deployed combat forces," the air force said in a brief statement.

The "RQ" prefix for the aircraft indicates an unarmed drone, unlike the "MQ" designation used for Predator and Reaper aircraft equipped with missiles and precision-guided bombs.

Aviation experts dubbed the drone the "Beast of Kandahar" after photographs emerged earlier this year showing the mysterious aircraft in southern Afghanistan in 2007.

The image suggested a drone with a radar-evading stealth-like design, resembling a smaller version of a B-2 bomber.

A blog in the French newspaper Liberation published another photo this week, feeding speculation among aviation watchers about the classified drone.

The air force said the aircraft came out of Lockheed Martin's "Skunk Works," also known as Advanced Development Programs, in California -- the home of sophisticated and often secret defense projects including the U-2 spy plane, the F-22 fighter jet and the F-117 Nighthawk.

The photo of the drone in Afghanistan has raised questions about why the United States would be operating a stealth unmanned aircraft in a country where insurgents have no radar systems, prompting speculation Washington was using the drones for possible spying missions in neighboring Iran or Pakistan.

The Sentinel was believed to have a flying wing design with no tail and with sensors built into the top side of each wing, according to published photos.

The RQ-170 is in line with Defense Secretary Robert Gates' request for more intelligence and surveillance resources and with the Air Force chief of staff's plans to expand the fleet of unmanned aircraft, the air force said.

The new drone is flown by the 30th Reconnaissance Squadron out of Tonopah Test Range in Nevada, which is under Air Combat Command's 432nd Wing at Creech Air Base, also in Nevada.

The United States has carried out an extensive bombing campaign against Al-Qaeda figures in Pakistan using the Predator and larger Reaper drones.

Robots or "unmanned systems" in the air and on the ground are now deployed by the thousands in Iraq and Afghanistan, spying from the sky for hours on end, searching for booby-traps and firing lethal missiles without putting US soldiers at risk.