Russia's Kommersant said Moscow had signed an S-300 contract with Tehran, but would not rush to implement it due to a seeming thaw in Russia's relations with the new U.S. administration.
Iranian media have repeatedly said, citing senior security officials, that Russia has started delivering elements of the advanced version of the S-300 missile with a range of over 150 kilometers (over 100 miles).
The reports have alarmed the U.S. and Israel, both of which have refused to rule out the possibility of military action against Tehran, accusing it of a failure to obey international nuclear non-proliferation demands.
However, Russia has dismissed the reports. "We do not supply any offensive weapons to Iran, and accusing Russia and Iran of cooperation that undermines regional security is unjust," Russian Deputy Foreign Minister Sergei Ryabkov said earlier.
Iranian Defense Minister Mostafa Mohammad Najjar said ahead of his visit that Tehran would negotiate the delivery of S-300 missiles "when it is necessary."
In an official statement, the Islamic Republic's Defense Ministry said: "During his trip to Russia, the Iranian defense minister will hold talks with Russian officials and visit a number of defense industry companies. The main purpose of the visit is the expansion of bilateral [military-technical] ties and the implementation of existing agreements in the military-technical sector."
"The contract on the S-300 could be fulfilled any time," Kommersant said, citing an unidentified Russian defense official. "New deals are in the offing. Talks on Buk-M1 medium-range missile systems are continuing. However there has been no political decision, necessary for the deals to go ahead."
Russian Foreign Minister Sergei Lavrov is expected to meet with the new U.S. Secretary of State Hillary Clinton, in March. The meeting is seen as a sign of a thaw in relations between Moscow and Washington, strained of late over a host of issues, including U.S. plans to deploy missile shield elements in Central Europe, which Russia strongly opposes.
Media reports said the new U.S. administration was seeking a compromise on the missile shield dispute that would be linked to Russia's cooperation in preventing Iran from building a nuclear bomb. The "Iranian threat" was one of the reasons cited for the missile shield.
Iran recently took delivery of 29 Russian-made Tor-M1 air defense missile systems under a $700-million contract signed in late 2005. Russia has also trained Iranian Tor-M1 specialists, including radar operators and crew commanders.