Syrian rebels say they captured an air defense base with a cache of missiles outside Damascus, a rare advance in a city where President Bashar Assad's forces have them on the back foot.

A video posted on YouTube shows dozens of rebels dressed in army fatigues celebrating as black smoke rises from a military installation behind them.

A middle-aged man holding an assault rifle says the assault on the base, in the Eastern Ghouta area was carried out by a rebel battalion from the town of Douma - both places are a few miles east of the capital.

Rebels say the operation happened on Thursday.

Syrian rebels are vastly outgunned by the army and have few ways to fend off continuous air attacks. Another video showed rebels at the base's weapons cache which included what appeared to a be part of a surface-air-missile.

It is unlikely that rebels have the ability to fire the missile but they might be able to use the explosives to make improvised bombs. When rebels have captured army bases in other parts of the country during the 18-month-old revolt, fighter jets have bombed the sites shortly afterwards.

It was not possible to independently verify the videos.

Access to Syria for foreign journalists is restricted by the Syrian government.

Rebels have positioned themselves in the suburbs of Damascus and the army has used jets, helicopters and artillery to batter residential areas.

A video taken by an opposition activist showed what he said was a pro-Assad militia firing artillery from a hill onto the northwestern Damascus suburb of Qudsayya where rebels have been fighting government forces.

In eastern Damascus, rebels said they had captured an officer from the elite Republican Guard on Friday and provided video footage of a man who identified himself as Colonel Ahmad Reaidi.

Around 180 people were killed in Syria on Thursday, including 48 of Assad's men, the Britain-based Syrian Observatory for Human Rights, a monitoring group, said.

Meanwhile, Syrian warplanes and artillery pounded on Friday the central city of Homs, subjecting the former rebel stronghold to its worst bombardment in months, activists said.

The reported bombardment by tanks and mortars as well as aircraft comes alongside a push by government force on another front, the embattled northern city of Aleppo.

The stepped-up pace of government attacks on Syrian cities suggests that the Damascus regime's forces have not been distracted by escalating tensions with its northern neighbor, Turkey. Ankara's parliament on Thursday authorized cross-border military operations after a Syrian shell killed five civilians on Turkish territory the day before.

Homs has been one of the flashpoints of the 18-month old uprising against Assad's regime. The focus of fighting has shifted to other areas in recent months, including Aleppo, since a government offensive against rebel strongholds in Homs ended in April.

The Britain-based Syrian Observatory for Human Rights said Friday's attack is the worst the city has seen in five months. The Observatory, which relies on a network of activists on the ground, said tanks and mortars as well as aircraft had bombarded the city's Khaldiya neighborhood.