A heavy firefight broke out on Monday between Free Syrian Army rebels and forces loyal to President Bashar al-Assad in a main district of the capital Damascus, witnesses said.

The sound of heavy machineguns and rocket-propelled grenades echoed through the night from the western neighbourhood of al-Mezze, one of the most heavily guarded areas of the capital and home to several security installations, residents told Reuters by telephone.

There is fighting near Hamada supermarket and the sound of explosions there and elsewhere in the neighbourhood. Security police have blocked several side streets and the street lighting has been cut off, a housewife who lives in the area said.

Extra troops have been patrolling in Mezze, located on the Damascus-Beirut road, after thousands of demonstrators took to the streets in the neighbourhood last month to denounce Assad following the killing of several protesters.

Security in the district is already heavy. Along with embassies and secret police complexes, several security officials have homes in the district, including Assef Shawkat, President Bashar al-Assad's brother-in-law and one of the central figures in the security apparatus underpinning the family-based power structure.

(Reporting by Khaled Yacoub Oweis, Amman newsroom; Editing by Michael Roddy)