Khaled Khoja, head of the National Coalition for Syrian Revolutionary and Opposition Forces, said Thursday that Russia had only fired "a few missiles" at DAESH targets in Syria.
"Russia has only launched a few missiles at DAESH." Khoja said during a panel discussion in Turkish capital, Ankara, organized by the Foundation for Political, Economic and Social Research (SETA), a Turkish think-tank.
"I have never heard of them [DAESH] sustaining serious losses [as a result of Russian airstrikes]," he added.
"Many civilians have been killed in [the Syrian cities of] Raqqa and Deir ez-Zor," Khoja noted, going on to assert that some 600 civilians had been killed by Russia’s ongoing air campaign in Syria, now in its third month.
The opposition leader added: "The regions Russia is currently bombing are entirely controlled by the [moderate] Free Syrian Army."
"Invading forces should retreat; safe zones should be established; and civilians should be protected," Khoja said. "Only then can we talk about a political solution to the crisis."
While the Kremlin says its air campaign -- which began on Sept. 30 -- is targeting DAESH, members of the western NATO alliance accuse it of targeting moderate groups opposed to Assad, including some that enjoy US and Turkish support.
At least 250,000 people have been killed since the Syrian conflict began in 2011, according to UN figures, while another 7.6 million have been internally displaced and over four million have fled to neighbouring countries.