Russian athletic-doping whistle-blower Vitaly Stepanov says he has audio recordings of a former Russian athletic official admitting that at least four Russian gold medalists from the 2014 Winter Olympics in Sochi were using banned performance-enhancing drugs.
Speaking to the U.S. television program 60 Minutes on May 8, Stepanov said he has audio recordings of 15 hours of conversation with Grigory Rodchenkov, the former head of Russia's drug-testing laboratory.
He did not name the athletes allegedly involved.
Stepanov also said that agents of Russia's Federal Security Service (FSB) were working as "doping controls officers" at the Sochi games.
"The FSB tried to control every single step of the anti-doping process in Sochi," Stepanov said.
Ben Nichols, a spokesman for the World Anti-Doping Agency (WADA), said the agency has reviewed Stepanov's interview and regards the allegations as "very disturbing."
"We will look into these without delay," he told Reuters.
Russia's national anti-doping agency has been decertified, and Moscow is scrambling to meet requirements to allow its track-and-field athletes to compete at the Summer Olympic Games in Rio de Janeiro in August.
