Activists: Syrian warplanes pound Homs

Syrian regime forces have battered Aleppo as Turkish forces hammer their positions for a second day. (AAP)

Syrian regime forces have battered Aleppo as Turkish forces hammer their positions for a second day. (AAP)

Stepped-up attacks on Syrian cities suggest that the Damascus regime's forces have not been distracted by escalating tensions with Turkey.

Syrian warplanes and artillery have pounded the central city of Homs, subjecting the rebel stronghold to its heaviest bombardment in months, activists say.

The reported tank and mortar shelling as well as airstrikes on Friday come 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 neighbour, Turkey.

Ankara's parliament on Thursday authorised cross-border military operations after a Syrian shell killed five civilians on Turkish territory the day before.

Activist Mohammed Saeed, based in the Damascus suburb of Douma, said rebels captured an air defence base in the Eastern Ghouta area near the capital.

A video showed dozens of gunmen outside an area where smoke was billowing. One of the gunmen said a "missile air defence battalion" was captured. Another video showed missiles inside a room.

Saeed said the rebels captured the base on Monday, but the videos were released late on Thursday, three days after the operation. They gave no reason for the delay.

The rebels did not give any other evidence that would confirm the capture of a base, or identify the location of the video.

If confirmed, the capture of a stock of working anti-aircraft missiles would be a boost to a lightly armed force that says it faces frequent attacks by low-flying helicopters and warplanes.

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 slowed down in April.

The Britain-based Syrian Observatory for Human Rights said Friday's attack is the worst Homs has seen in five months. The Observatory, which relies on a network of activists on the ground, said the bombardment had hit the city's Khaldiya neighbourhood.

"Around dawn, the regime went crazy and started shelling hysterically," a Homs-based activist known as Abu Rami told AP via Skype on Friday. "An average of five rockets a minute are falling." Abu Rami was speaking from the central rebel-held old quarter known as Old Homs. He asked to be identified by his nickname for fear of reprisal.

He said the government forces are mainly firing rockets and heavy mortars at the rebel-held neighbourhoods of Old Homs, Khaldiya, Qusour and Jouret el-Shayah.

Abu Rami also said the regime forces have been shelling villages around Homs and the rebel-held town of Rastan, just north of the city.

He said there were no immediate reports of casualties, adding that most residents living in rebel-held areas are hiding in shelters.

Activists say most government forces near Homs are stationed outside the town. Homs is Syria's third largest city. Regime forces pounded parts of Homs for months, leaving large swaths of the city in ruins by April.

The uprising against Assad erupted in March 2011 and morphed into a bloody civil war, killing more than 30,000 people, activists say.

The Observatory also said Syrian military has been shelling the neighbourhood of Sakhour in Aleppo as government forces battle rebels in the country's largest city.