A rebel Free Syrian Army group claimed it had shot down an army helicopter in Damascus on Monday and that the pilot had been killed, a spokesman said.

"It was in revenge for the Daraya massacre," Omar al-Qabooni, a spokesman for the Badr Battalion in Damascus told AFP via Skype, referring to the reported killing of at least 320 people in a town southwest of Damascus during a five-day government offensive.

He said the rebels had found the body of the pilot after the burning aircraft crashed to the ground in the district of Qaboon during heavy shelling and fierce fighting in the area.

State television said a helicopter crashed without giving more information.

An anti-regime activist who identified herself as Alexia also told AFP via Skype: "It was the Free Syrian Army for sure."

The claims could not be independently verified.

Syrian rebels claimed to have shot down a warplane on August 13 in the eastern province of Deir Ezzor.

The Syrian Observatory for Human Rights said it believed the helicopter "was hit while it was being used in fighting nearby."

It reported clashes between troops and the FSA in several areas of Damascus, including Qaboon and the neighbouring district of Jubar -- where anti-regime sentiment is strong -- and several nearby towns east of the city.

The violence flared a day after the Observatory reported the discovery of hundreds of bodies in Daraya after what opposition militants said was a "massacre" by government troops.