Russia's Foreign Ministry has dismissed as groundless a recent claim by a U.S. nonproliferation expert that Moscow is helping Iran build nuclear weapons.

Henry Sokolski, executive director of the Washington-based Nonproliferation Policy Education Center, wrote an article for the Washington Times last week making various allegations over Russian involvement in an Iranian nuclear weapons program.

The ministry said in its statement: "The emergence of nuclear weapons in Iran would be just as unacceptable to us as to the United States. We have said this several times. So claims that Russia is helping Iran to build nuclear weapons are entirely unfounded."

In his article, Sokolski cited "leaked International Atomic Energy Agency (IAEA) documents" as saying Iran is working on a nuclear warhead "small and light enough to enable Iran's latest rocket systems to target NATO's southeastern members".

He said Russians "have been helping Iran complete a heavy water reactor at Arak that is optimized to make weapons usable plutonium," and cited a U.S. intelligence report as saying Russia is helping Iran build a rocket capable of carrying a nuclear warhead.