The Syrian Observatory for Human Rights reported Sunday that Islamic State fighters had seized control of the town of al-Qaryatayn in Homs province, part of a wider counterattack by the jihadists as they resist a fierce offensive in eastern Syria.
There was no comment from the Syrian army on the report that Qaryatayn, 120 kilometers (70 miles) northeast of Damascus, had fallen.
Syrian government forces recovered Qaryatayn from Islamic State some six months ago. The Observatory said Islamic State fighters had seized control of Qaryatayn in a surprise attack launched after its fighters had infiltrated the town.
Islamic State has lost swathes of territory to the Russian-backed Syrian government and to U.S.-backed Syrian militias that are waging separate campaigns against the jihadist group's last major strongholds in Deir el-Zour province in eastern Syria.