"This is not conducive to normalization in that country and fuels violence,” Gatilov told a news conference hosted by RIA Novosti.
The arming of one party to the conflict significantly complicates the attempts to get the opposing sides to negotiate, he said without naming the "foreign arms suppliers.”
Gatilov reiterated Russia’s official position that it will not carry out fresh arms deliveries to the Syrian government, but is only supplying arms and military equipment under contracts signed before the civil war, which has claimed some 70,000 lives according to the latest UN estimates.
Foreign Minister Sergei Lavrov said on Mondaythat Moscow had not tried to smuggle arms components into Syria via Finland.
Finnish Customs authorities reported last week they were investigating the origins of a container with spare tank parts that was unloaded from a ship at Helsinki’s Vuosaari Harbor in January. Carrier Finnline said the container held military equipment, but did not identify its owner.
On Friday, Lavrov said there are no Russian troops in Syria apart from several dozen technical staff at the Tartus naval support facility.
Russia’s state-run arms dealer Rosoboronexport said on Wednesday it is supplying air-defense missile systems and maintenance and servicing equipment to Syria, but not combat aircraft.
Russia has repeatedly denied media reports that it was sending warships to Syria and delivering weapons to Damascus.