A monitor said fierce clashes between ISIS and pro-regime forces in central Syria had left over 150 fighters dead in 24 hours, mostly terrorists, according to AFP on Sunday.
The Britain-based Syrian Observatory for Human Rights said 120 ISIS terrorists "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."
The town is ISIS’ last bastion in the central province apart from a handful of small villages.
Pro-government forces seized Uqayribat on Friday night, but ISIS responded with a counter-offensive on Saturday that left it in control of most of the town, Observatory chief Rami Abdel Rahman said.
An intense barrage of artillery fire and Syrian and Russian air strikes on ISIS’ positions allowed pro-regime forces on Sunday morning to push the terrorists back out of the town and advance on villages to the west that remain under ISIS control.
ISIS has controlled Uqayribat since 2014, using it to launch attacks on regime-held areas and a strategically vital road Abdel Rahman described as "the only lifeline for the regime between Aleppo and central and southern Syria".
Regime forces, backed by heavy Russian air strikes, launched a major assault on ISIS-held parts of Hama in June.
"By consolidating their control of (Uqayribat) and ousting ISIS from the surrounding villages, regime forces could oust the organization from the whole of Hama province," Abdel Rahman said.
Other rebel groups still control parts of the province's rural north.
Hama, which borders on six other Syrian provinces, is strategically vital to the Assad regime, separating opposition forces in Idlib from Damascus to the south and the regime's coastal heartlands to the west.
ISIS has suffered multiple defeats across Syria and neighboring Iraq in recent months, notably in its main Syrian base of Raqqa.
On Friday a US-backed Kurdish-Arab coalition seized Raqqa's Old City and was advancing on the terrorists in the heavily defended city centre.
The Syrian Democratic Forces (SDF) began their offensive in May, capturing the city of Tabqa and a key dam nearby before entering Raqqa city in early June.
Meanwhile, pro-regime forces have advanced against ISIS in the eastern part of Homs province and western Deir Ezzor, where they have come to within 19 kilometers of the provincial capital.
Syria's conflict has killed more than 320,000 people and displaced millions since it started with anti-government demonstrations in 2011.