Russia is not currently implementing its planned sale of sophisticated S-300 air defense systems to Iran, a top official with the state office for arms sales told Interfax.
"Nothing is happening. Supplies are not taking place," said Alexander Fomin, deputy head of the Federal Service for Arms Cooperation, at an arms fair in Rio de Janeiro.
Russia's plans to provide the systems to Iran have attracted criticism from the United States and Israel, neither of which have ruled out attacks on Iran's controversial atomic facilities.
The comment came after an unnamed official at the same agency said last month delivery of the defense systems, intended to shield key areas from attack, would depend on the "developing international situation and the decision of the country's leaders."
Moscow's decision to hold back on the sales partly reflects international pressure but also warming ties between Russia and the United States, a chief adversary of the Islamic republic.
This month Russia also said it was making its first ever purchase of reconnaissance drones from Israel, reflecting closer ties with the Jewish state in the defense sphere.