"Turkey should not be part of Western alliance, or NATO. It is the most dangerous country… they are supporting those groups who have become the greatest threat to our national security," he said.
Ribal Assad, whose organization is based in London, explained the support for Islamists "is exactly what Turkey has been doing." He added that Turkey backed groups who "want to create an Islamic State all over the world, not just in the Middle East."
The Syrian president himself has accused Turkey of providing troops, weapons, intelligence data and financial support to Syrian militants while buying smuggled oil from the Islamic State jihadist group (known as Daesh in the Arab world).
In a briefing on Wednesday, the Russian Defense Ministry provided satellite images showing Daesh, outlawed in Russia, transporting up to 200,000 barrels of oil in at least 1,722 trucks to third-party countries, most notably Turkey on the northern border.
On Thursday, President Vladimir Putin in his address to the parliament said Russia was aware who in Turkey was earning money from the stolen oil and recruitment of fighters, adding that no contacts or business with terrorists should be allowed.