"One cannot say today that Iran can create nuclear weapons and the means of delivering them," The Telegraph quoted Vladimir Voronkov, head of the Russian foreign ministry's department of European cooperation, as saying.
The Interfax and ITAR-TASS news agencies quoted Voronkov as saying further that he had reached his conclusions on the basis of information supplied by Moscow's intelligence services.
Western countries, which believe that Iran is using an ostensibly peaceful atomic programme to secretly develop nuclear weapons, have persuaded the United Nations to impose economic sanctions on Tehran.
Yet Russia has greater access to Iran's nuclear programme than most countries: one of its companies, Atomstroyexport, is building the Bushehr reactor on the humid Gulf coast, giving teams of Russian engineers first-hand contact with their Iranian counterparts.
It is also a key supplier of military hardware to the Islamic republic, including the anti-missile defences that now protect its nuclear sites.
While the West has pushed hard for action against Iran, Russia has advocated a softer approach.