MONTREAL • The World Anti-Doping Agency (Wada) said on Tuesday that it is investigating fresh claims of Russian doping involving four Sochi 2014 Winter Olympics gold medallists.
The allegations - the latest in a slew of doping accusations to rock Russian sport - were made by whistle-blower Vitaly Stepanov in an interview aired on Sunday by American channel CBS.
While Russia has dismissed the claims as an attempt to derail upcoming Wada talks, the anti-doping agency expressed its concern.
"Wada will probe these new allegations immediately," its president Craig Reedie said in a statement.
"The claims made in the programme offer real cause for concern, as they contain new allegations regarding attempts to subvert the anti-doping process at the Sochi Games."
Russia won 13 golds at the Sochi Winter Olympics. The names of the alleged drug cheats were not revealed in the CBS programme.
Wada will host meetings of its executive committee and its foundation board in Montreal later this week where they are expected to discuss doping in Russian sport, among other topics.
The claims made in the programme offer real cause for concern, as they contain new allegations regarding attempts to subvert the anti-doping process at the Sochi Games.
CRAIG REEDIE, World Anti-Doping Agency president, on the new claims of doping by Russian athletes at the 2014 Sochi Winter Olympics.
A Wada independent committee concluded in a report published in November that there was evidence of "state-sponsored" doping and mass corruption in Russian athletics.
The International Association of Athletics Federations (IAAF) suspended Russia over the report, with the IAAF council due to decide in June if the country's athletes can compete at August's Rio Olympics.
In Sunday's interview, Stepanov - a former Russian Anti-Doping Agency (Rusada) official - cites Grigory Rodchenkov, former head of Russia's now-discredited drug-testing lab, as telling him that state security service (FSB) officers "tried to control every single step of the anti-doping process in Sochi".
Reedie said: "Mr Rodchenkov was of course interviewed by Wada's Independent Commission that exposed widespread doping in Russian athletics last year.
"Yet, regrettably, he was not forthcoming with such information related to the Sochi Games. It is surprising to hear these views so many months after the Commission concluded its work."
On Monday the Russian sports ministry said it was "certain about the transparency of doping control during the Olympic Games".
And on Tuesday Natalia Jelanova, an adviser to the Russian sports ministry, said: "We are worried of course over Stepanov's comments, although he has no link with (Russian) anti-doping bodies."
She added in an interview with R-Sport that Russia is ready to provide Wada with any documents it requests.
Reedie, meanwhile, highlighted the part played by Stepanov and his wife, banned 800m runner Yuliya Stepanova, in laying bare the extent of doping in Russia.
"There is no question that the Stepanovs provided vital information and intelligence that allowed the Commission to be established; and, without which, widespread doping in Russian athletics may never have truly been exposed," he said.