Battles have been ongoing in Syria's vast Badia desert since the start of the month, with government forces supported by Russian aircraft.
On Tuesday, clashes and Russian air strikes killed 13 militants died in fighting, the so-called Syrian Observatory for Human Rights said.
The battles centered around Ithriya, in Hama province, and further east, near where the provincial borders of Hama, Aleppo and Raqa meet.
Mobile Daesh units have remained active in the Syrian desert since the militants lost the last shred of their self-proclaimed caliphate in March last year.
Daesh overran large parts of Syria and Iraq in 2014, declaring a proto-state there, before several campaigns in both countries led to its territorial defeat.