The World Anti-Doping Agency (WADA) on Tuesday said it was investigating fresh claims of Russian doping involving four Sochi 2014 Winter Olympics gold medallists.
The allegations - the latest in a string of doping accusations to rock Russian sport -- were made by whistleblower Vitaly Stepanov in an interview aired on Sunday by American channel CBS.
While Russia have 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,” WADA President Craig Reedie said in a statement.
“The claims made in the program 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 gold medals 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.
A WADA independent committee concluded in a report published in November 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 the Rio Olympics.