A huge explosion shook the Mezze military airport on the western edge of Damascus on Sunday.

Video purportedly taken by activists showed flames rising from the compound, home to some of President Bashar al-Assad's elite forces.

Reuters is unable to independently verify the content of the video.

The British-based Syrian Observatory for Human Rights reported that the attack killed or wounded around 20 members of Assad's forces.

The Syrian conflict began as a non-violent uprising two years ago, and has since morphed into a violent fight between Assad and his foes across the country, including here in Aleppo.

Over the weekend, Syrian rebels pleaded for advanced weapons from the United States, which had promised them unspecified military aid.

But Western powers have been reluctant to arm Syrian insurgents, fearing that the weapons might fall into the hands of Sunni Islamists insurgents.