Clashes between Assad loyalists and the country's new Islamist rulers in the former president's coastal heartland have killed more than 1,000 people, mostly civilians, according to a war monitoring group.

The violence broke out when gunmen loyal to ousted president Bashar al-Assad ambushed a Syrian security patrol near the port city of Latakia.

At least 240 people have been killed in northwest Syria as fierce clashes escalate between government forces and loyalists of former President Bashar al-Assad, marking the deadliest violence since the fall of Assad three months ago.