Around 120 Daesh militants and 35 Syrian regime troops died during fighting after in Hama, Britain-based war monitor Syrian Observatory for Human Rights says.
Fierce clashes between Daesh and pro-Syrian regime forces in central Syria have left over 150 people, mostly Daesh militants, dead in 24 hours, a war monitor said on Sunday.
The Britain-based Syrian Observatory for Human Rights said 120 Daesh militants "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 Daesh's last bastion in the central province apart from a handful of small villages.
Pro-regime forces seized Uqayribat on Friday night, but Daesh 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 regime and Russian air strikes on Daesh positions allowed pro-regime forces on Sunday morning to push the militants back out of the town and advance on villages to the west that remain under Daesh control.
Daesh 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 Daesh-held parts of Hama in June.
"By consolidating their control of (Uqayribat) and ousting Daesh from the surrounding villages, regime forces could oust the organisation 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.
Meanwhile, Syrian regime and allied forces have advanced further towards a government enclave of Deir Ezzor besieged by Daesh in the country's east, Syrian Observatory for Human Rights also said on Sunday.
Syria's army, backed by Russian military support, has been advancing towards Deir Ezzor city for weeks on several fronts.
On Sunday, forces advanced to within 10 kilometres (six miles) to the west of the city, the provincial capital, and a besieged military base.
They also seized the Al-Kharata oilfield in resource-rich Deir Ezzor province, the monitor said.
Daesh have held much of Deir Ezzor province and besieged government forces and civilians inside Deir Ezzor city since 2015.
An Daesh evacuation convoy trying to reach Daesh territory in east Syria has split in two, with some buses remaining in the open desert after others turned back into government-held areas, a US-led coalition fighting the group said on Sunday.
The Syrian regime and Lebanon's Shia Hezbollah group offered the convoy of about 300 lightly armed militants and about 300 family members safe passage a week ago in return for Daesh surrendering an enclave on the Syria-Lebanon border.
However, the coalition has blocked the convoy from entering Daesh territory in east Syria, near the border with Iraq, by cratering roads and destroying bridges, saying it opposes the evacuation deal as being "not a lasting solution".
"One group remains in the open desert to the north west of Al-Bukamal and the other group has headed west towards Palmyra," the coalition said in an emailed statement.
On Saturday, Hezbollah said all but six of the buses had safely crossed out of Syrian regime territory and were no longer the responsibility of it or the Assad regime.
It warned the United States that the buses in the desert included elderly people, pregnant women and casualties, and accused it of stopping humanitarian aid reaching the convoy.
The coalition said it had contacted Russia to deliver a message to the Syrian regime that it would still not let the convoy pass, and that it had offered suggestions on how to save the civilians in it from suffering.
"Food and water have been provided to the convoy," it said, without giving further details.
The coalition has said it will not target the convoy directly while it contains civilians, but said in its statement it had struck about 85 Daesh militants near the convoy.
It had also struck about 40 Daesh vehicles near the convoy including a tank, an artillery system, armed vehicles and transport vehicles seeking to help move the militants in the convoy into its territory, it said.