The head of the High Committee of the Syrian opposition, Riad Hijab, said Syria's Bashar Assad and regime allies such as Russia and Iran escalate the catastrophic war by using internationally banned weapons, including cluster bombs and munitions.
Speaking to Anadolu Agency on Sunday, he said: "We have seen an unprecedented escalation by the regime and its allies Iran and Russia against the Syrian people, using banned weapons such as [white] phosphorus and napalm bombs."
Hijab said that the Syrian opposition has suspended its participation in the U.N. peace talks due to massacres committed by the regime on Syrian civilians.
"Any return to negotiations would require creating a favorable climate, which currently does not exist," he said.
Footage of Russian warplanes targeting civilians in Syria's second largest city of Aleppo while using white phosphorus munitions emerged over the weekend.
White phosphorus is an incendiary and toxic chemical substance that is banned by the international treaties and its usage constitutes a war crime. The video dated June 8 shows the Russian warplanes targeting Handarat area located just north of Aleppo city center, according to Turkish military sources.
In the footage, white phosphorus is seen dropped by Russian warplanes, while burning in the air and on the ground amid explosions with white smoke.
Two children were reportedly killed and six civilians were injured in the attacks.
The usage of these munitions on civilian areas is a clear violation of United Nations Convention on Certain Conventional Weapons dated 1980 and constitutes a war crime, the sources said.
This is not the first time that Russia has used such internationally banned weapons and committed war crimes. According to a report from the Washington-based think tank Center for Strategic and International Studies (CSIS) in February, Russia has been recorded as it used cluster munitions on at least 20 occasions since Syria and Russia began their joint offensive on September 30. Human Rights Watch collected detailed information about attacks in nine locations that have killed at least 35 civilians, including five women and 17 children, and injured dozens.