Moscow said Saturday that its jets had destroyed an IS command post near the group's main Raqa stronghold as well as an underground bunker.
"Over the past 24 hours, SU-34 and SU-24M jets of the Russian airborne formation in Syria made more than 20 sorties over nine Islamic State infrastructure facilities," the defence ministry said.
The Syrian Observatory for Human Rights said Russian strikes "hit IS positions west of Raqa overnight and explosions were heard in the city".
Raqa has acted as the extremist group's de facto Syrian "capital" since 2013.
The Observatory, which relies on a network of sources on the ground for its information, said Russian jets had killed 12 jihadists in Raqa this week.
But raids ordered by Moscow have also hit areas controlled by moderate groups that are fighting Assad and even prompted a claim by US Senator John McCain that Russian jets had killed rebel soldiers trained and funded by the CIA.
Obama told reporters that Russia "doesn't distinguish between ISIL and a moderate Sunni opposition that wants to see Mr Assad go.
"From their perspective, they're all terrorists. And that's a recipe for disaster."
Russia said its strikes this week had completely destroyed IS positions in northern Aleppo province, neighbouring Idlib province and in Hama in central Syria.
But several military sources and the Observatory said Russia had hit areas controlled by groups other than IS.
The Observatory also says Russian strikes have killed several civilians and wounded doctors in a raid on a hospital in Hama.
British Defence Secretary Michael Fallon said that just five percent of Russian strikes had targeted IS.
SOURCE : MSN
