The Times wrote in December that the killers of former FSB agent Alexander Litvinenko used more than $10 million worth of polonium-210 to poison him.
"Preliminary findings from the post mortem examination on the former KGB spy suggest that he was given more than 10 times the lethal dose," the British daily said.
The source told RIA Novosti: "People giving such improbable figures for the cost of the polonium-210 that was used to poison Litvinenko have no real information. The total cost of polonium-210, which Russia supplies to the U.S., does not exceed several tens of thousands of dollars, and Litvinenko could have died of a considerably smaller amount of this radioactive isotope."
The Times also wrote: "United Nuclear Scientific Supplies of New Mexico, one of the few companies licensed to sell polonium-210 isotopes online, said that as a single unit cost about $69, it would take at least 15,000 orders, costing more than $10 million, to kill someone."
A high-ranking source in the Russian nuclear agency told RIA Novosti in early December that the only reactor in Russia able to produce polonium-210 was shut down two years ago.
He said Russia has produced eight grams of polonium monthly from reserves that remain in stock following the reactor's shut-down.
"We have supplied it [polonium-210] to U.S. companies, and there were deliveries to British firms. The eight grams we have produced cannot have disappeared in Russia, but we do not keep track of the material after selling it," the source said.
Polonium supplies to the United Kingdom ended in 2001.