TEHRAN, April 18. /TASS/. The Russian-Iranian relations are a factor of peace and security in the region, Ali Akbar Velayati, a senior adviser to Iran’s supreme leader Ayatollah Ali Khamenei, said on Monday.

"Iran-Russia ties are at beginning stages while so far the two countries’ collaborations in Syria have been significant in overcoming ISIL (Islamic State) and terrorists," the Mehr news agency quoted Velayati as saying.

"We perceive a bright future to the ties between Iran and Russia as they lead to peace and security in the region," he stressed.

Speaking on the S-300 missile systems, Velayati said "the delivery gives substance to the fact that Iran-Russia relations are being pursued seriously and the arrival of the in-time Russian long range surface-to-air missile systems will effectively help Iran to defend possible aggressions."

Russian Deputy Prime Minister Dmitry Rogozin said in an interview with Echo Moskvy radio station last week that Russia started delivering S-300 air defense missile systems to Iran and the deal was expected to be fulfilled before the year-end.