Russian fighter jets on Wednesday carried out 20 flights in Syria, striking "eight Islamic State targets" including a command post held by the jihadist group, the Russian defence ministry said.
"The targets, notably a command centre of the terrorists, were completely destroyed," the ministry said in a statement.
Defence ministry spokesman Igor Konashenkov, quoted by Russian news agencies, added: "All the strikes took place after air reccies following information provided by the Syrian government."
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The ministry also published a video of the air strikes which appeared to show three targets being hit. It said "munitions and weapons depots and military equipment" were also destroyed in Wednesday's raids.
But the United States was quick to contradict Moscow's claims of hitting IS targets.
"It does appear (the strikes) were in areas where there were probably not ISIL forces," US Defense Secretary Ashton Carter said, using an alternative acronym for the IS group.
President Vladimir Putin earlier Wednesday defended the decision to stage Russia's first air strikes in Syria, saying: "The only correct way to fight international terrorism... is to act preemptively, to battle and destroy fighters and terrorists on the territories they have already seized, not to wait for them to come to us."