The Islamic State group has captured more than a dozen villages and hills during a fresh offensive in northern Syria, opposition activists said Saturday. The ISIS territorial gains bring the extremist group close to the main highway that links the capital, Damascus, with the country’s largest city of Aleppo.

IS also clashed with rival insurgent groups near the border with Turkey where they have been on the offensive for days, forcing tens of thousands of residents to flee toward safer areas near Turkey.

The Britain-based Syrian Observatory for Human Rights said the fighting between ISIS and government forces is concentrated in areas east of the town of Khanaser, which has changed hands several times in recent months. […]