The Syrian Observatory for Human Rights gave no immediate reports of casualties in the violence, which comes a day after 194 people were killed in bombings, shellings and clashes across the country.

Security forces fanned out across parts of the capital on Sunday and roads were cut after fierce battles at dawn between rebels and troops near a political intelligence office in northwestern Damascus, the Observatory said.

As the fighting raged, warplanes carried out three raids on the Ghuta region that lies about 50 kilometres (30 miles) northeast of the capital.

Air strikes on Saturday killed 14 people in the Ghuta town of Zamalka, including eight children and four women, the Britain-based Observatory added.

Another 36 people died when government troops on Saturday shelled targets in the northwestern province of Idlib, where rebels fighting to topple the regime of President Bashar al-Assad seized new ground in the past few days.

The rebels said they had launched a major assault on the Taftanaz airbase in the province to stop helicopter gunships taking off from there.

The Observatory also reported army shelling on several neighbourhoods of the northern metropolis Aleppo as well as fighting in the southern town of Daraa, cradle of the uprising that erupted in mid-March 2011.

It says more than 36,000 people have been killed in the 19-month uprising which first started as a protest movement before becoming an armed rebellion in the face of brutal state repression.

The Observatory relies on a network of activists and medics in civilian and military hospitals for its figures which cannot be independently confirmed.