Moscow, May 29 (IANS/RIA Novosti): Russia’s delivery of S-300 air defence systems to Syria is a restraining factor against possible foreign interference in the Syrian conflict, Russian deputy foreign minister Sergei Ryabkov said Tuesday.

“We believe such steps are to a great extent restraining some ‘hot heads’ from considering scenarios in which the conflict may assume an international scale with the participation of outside forces,” Ryabkov said.

S-300 is widely acknowledged by defence analysts as one of the world's most advanced air defence systems.

The minister refused to say whether the Russian-made air defence systems had been already delivered to Syria.

“I can neither confirm, nor deny in what stage these deliveries are at,” Ryabkov said.

“We understand all the concerns and signals sent to us from various states. We see that this issue worries many of our partners. We have no reasons to reconsider our position in this sphere.”

The sale of Russian weapons to Syrian President Bashar Al-Assad’s regime has been a source of bilateral tension between Moscow and Washington, with US officials accusing Russia of arming a regime the US says is killing its own citizens in Syria’s raging civil war.

Last week US Secretary of State John Kerry said that the sale by Russia of S-300 air defence systems to Syria would be “destabilising” for the region.

Ryabkov reiterated that Russia is merely honouring previously-concluded agreements with Damascus by supplying S-300 systems to Syria.