The newspaper Kommersant reported that it had spoken to the 76-year-old Danilenko and quoted him as saying: "I am not a nuclear scientist and I am not the founder of the Iranian nuclear program."
Danilenko, an expert in a process that uses explosions to create tiny diamonds for a range of industrial uses, had worked in Iran in the 1990s. The Post said he told investigators from the International Atomic Energy Agency that he thought his work was limited to assisting civilian engineering projects.
Kommersant said that starting in the 1950s and until his retirement he had worked at one of the Soviet Union's top nuclear weapons research centers, known as Chelyabinsk-70.
After the 1991 collapse of the Soviet Union, he worked for the Ukrainian company Alit that produces what are called nanodiamonds, the paper reported. It cited the company's director, Vladimir Padalko, as saying that experts from the IAEA and the U.S. State Department had met with Danilenko several times in recent years.
Russia built Iran's first nuclear power plant in the southern port of Bushehr, which began producing electricity in September, and Russia's nuclear chief said Thursday that Iran would like more Russian-built reactors.
Rosatom chief Sergei Kiriyenko told a Cabinet session chaired by Prime Minister Vladimir Putin that his agency was working an agreement.
Russin and Iranian officials have discussed building more reactors in the past, but Kiriyenko's latest statement comes amid Western calls for sanctions on Tehran over the IAEA report released Tuesday that details suspected nuclear weapons-related advances. Russia has firmly rejected imposing any new sanctions on Iran.