A car bomb hit a police checkpoint in a town southwest of Damascus on Tuesday morning, as the army deployed in large numbers nearby in a bid to suppress insurgents there, a monitoring group said.

"A car bomb exploded at dawn, targeting a military police checkpoint in Jdeidet Artouz," said the Syrian Observatory for Human Rights. "This was followed by intense shooting, as regular troops continued to be deployed in the fields between Kfar Sousa and Daraya."

It was not immediately clear if anyone was killed by the car bomb or the fighting that ensued.

Kfar Sousa lies on the southern belt of the capital, with the small town of Daraya situated just a few kilometres (miles) to the southwest.

Fighting broke out in Damascus over the summer, pitting rebels and the army against each other in several southern districts of the capital.

Insurgents have developed rear bases in areas of Damascus province where anti-regime sentiment is strong, and which is home to some of the their best organised and fiercest groups.

The army is currently pushing to quell the rebellion there.

Elsewhere, clashes raged in the Hamdaniyeh district of Aleppo, Syria's commercial capital where fighting has reached a stalemate after five months of deadly urban combat.

More than 40,000 people have been killed in Syria since the uprising against President Bashar al-Assad broke out in March last year, according to the Observatory, which relies on a network of activists, doctors and lawyers for its data.