The Syrian Observatory for Human Rights said on Friday that 11 regime and allied fighters and seven jihadists were killed in clashes in an area of the Badia desert where the provinces of Raqa, Aleppo and Hama meet, and in another area in the east of Homs province.

Russian aircraft carried out strikes in support of their Syrian regime ally, the Britain-based Observatory added.

IS jihadists have retained a roving presence in Syria's vast Badia desert and regularly carry out attacks there, despite losing their last shred of territory in the country in March 2019.

Last week, 13 members of the pro-regime forces and 15 jihadists died in the northern province of Raqa in similar circumstances, while in August the jihadists claimed an attack that killed a Russian general near the city of Deir Ezzor.

And at the start of July, the Observatory said 20 pro-government fighters and 31 jihadists died in two days of clashes in the province of Homs.

IS jihadists declared a "caliphate" in large swathes of Syria and neighbouring Iraq in 2014, implementing their brutal interpretation of religion on millions under their rule.

But various campaigns against them in both countries whittled away at that proto-state, before Kurdish-led forces expelled them from their last patch of territory last year in Syria's far east.