The battles are raging in the Athraya region in the northern countryside of Hama, in which the Syrian army is making progress, said the Syrian Observatory for Human Rights.
The UK-based watchdog group added that the army has captured new hilltops in that area.
Meanwhile, the state news agency SANA said at least 23 militants were killed on Thursday during the fighting in the areas of Latamneh, Kafr Zaita, and Kafr Nabuda in the countryside of Hama.
SANA said the slain militants were with the Turkey-backed Jaish al-Fateh, or the Conquer Army, militant group. It added that the military operation in northern Hama also destroyed the militants’ weaponry and military gears.
In the eastern province of Deir al-Zour, airstrikes by the U..S-led anti-terror coalition struck areas in the al-Jafra oilfield which is under the IS’ control, leaving unknown losses, according to the Observatory.
It added that Russian warplanes also struck the vicinity of the government-controlled airbase of Deir al-Zour, where the IS has been trying to storm repeatedly.
The Syrian army, backed by the Russian warplanes, have been making notable progress recently, raising the ire of regional backers of the insurgent groups, such as Turkey and Saudi Arabia who recently said they are ready to send ground troops to Syria under the pretext of fighting the IS, but the claim have been dismissed by Damascus analysts as a move aiming at complicating the Syrian conflict and propping up the jihadi groups.