Russian air strikes Saturday targeting the Islamic State group in Syria have sown "panic", forcing some 600 "militants" to abandon their positions and head to Europe, Moscow claimed.

"Our intelligence shows that militants are leaving areas under their control. Panic and desertion have started in their ranks," Colonel General Andrei Kartapolov, a senior official with the Russian General Staff, said in a statement. "Some 600 mercenaries have abandoned their positions and are trying to find their way into Europe."