Syrian leader Ahmed al-Sharaa called for peace on Sunday after hundreds were killed in coastal areas in the worst communal violence since the fall of Bashar al Assad.

"We have to preserve national unity and domestic peace, we can live together," al-Sharaa, the interim president, said as clashes continued between forces linked to the new Islamist rulers and fighters from Assad's Alawite sect.

"Rest assured about Syria, this country has the characteristics for survival," al-Sharaa said in a circulated video, speaking at a mosque in his childhood neighbourhood of Mazzah in Damascus. "What is currently happening in Syria is within the expected challenges."

Syrian security sources said at least two hundred of their members were killed in the clashes with former army personnel owing allegiance to Assad after co-ordinated attacks and ambushes on their forces that were waged on Thursday.

The attacks spiralled into revenge killings when thousands of armed supporters of Syria's new leaders from across the country descended to the coastal areas to support beleaguered forces of the new administration

The authorities blamed summary executions of dozens of youths and deadly raids on homes in villages and towns inhabited by Syria's once ruling minority on unruly armed militias who came to help the security forces and have long blamed Assad's supporters for past crimes.

The Syrian Observatory for Human Rights, a U.K.-based war monitor, said on Saturday the two days of fighting in the Mediterranean coastal region amounted to some of the worst violence for years in a 13-year-old civil conflict.

Clashes continued overnight in several towns where armed groups fired on security forces and ambushed cars on highways leading to main towns in the coastal area, a Syrian security source told Reuters on Sunday.