The Syrian Observatory for Human Rights group said scores of Syrian government forces have been killed in three days of fighting with Islamic State in the east of the country, where the jihadist group has attacked government-held areas, Reuters reports.

Syrian officials could not be reached for comment.

The Britain-based Observatory said 120 members of the Syrian government forces and 70 Islamic State fighters had been killed in clashes since Saturday, January 16.

The official news agency SANA reported on Monday that government forces had recaptured some residential areas taken by Islamic State in Begayliya, near the city of Deir ez-Zor, and killed a number of fighters.