The civil war in Syria has opened opportunities for foreign mercenaries and about 20,000, financed by Afghan drug trafficking, have been fighting in that Middle East country, according to Russia’s Federal Drug Control Service Director Viktor Ivanov.

“Transnational organized crime groups can ensure an inflow of a huge number of criminals and mercenaries from certain countries to any part of the world with proceeds from heroin sales,” Ivanov was quoted by the Ria Novosti news agency as saying on Thursday.

He said 15,000 to 20,000 mercenaries were concentrated in Syria “destabilizing the situation in that country,” he said without giving any evidence to support his claims. It was transnational criminal groups and not Taliban who pose the greatest threat in Afghanistan, he added.

Russian Foreign Ministry spokesman Alexander Lukashevich said earlier this month that Syria was turning into a “center of attraction” for international terrorists in the ongoing civil war between rebels and government forces.

The Syrian regime of President Bashar al-Assad last year had submitted to the U.N. Security Council lists of hundreds of foreign nationals killed fighting against government troops in that Arab country.

According to the U.N., about 70,000 people, mostly civilians, have been killed in Syria since an uprising aimed at ousting Assad from power broke out in March 2011.