A report by Britain-based Syrian Observatory for Human Rights (SOHR) said 120 IS fighters “were killed in clashes in and around the town of Uqayribat in the eastern Hama countryside, along with at least 35 regime troops and loyalist militiamen”, Xinhua news agency reported.
The town is the jihadist group’s last bastion in the central province apart from a handful of small villages.
Pro-government forces seized Uqayribat on Friday night, but IS responded with a counter-offensive on Saturday that left it in control of most of the town, SOHR chief Rami Abdel Rahman said.
An intense barrage of artillery fire and Syrian and Russian air strikes on jihadist positions allowed pro-regime forces on Sunday morning to push the jihadists back out of the town and advance on villages to the west that remain under IS control.
IS has suffered multiple defeats across Syria and neighbouring Iraq in recent months, notably in its main Syrian base of Raqqa.
Syria’s conflict has killed more than 320,000 people and displaced millions since it started with anti-government demonstrations in 2011.