LOS ANGELES (AFP) - Four Russian gold medallists at the 2014 Sochi Olympics were drug cheats, doping whistleblower Vitaly Stepanov alleges in an interview for an upcoming edition of CBS television's 60 Minutes.

In an interview to air in full on Sunday, Stepanov, a former official with the Russian Anti-Doping Agency (Rusada), cites Grigor Rodchenkov, former head of Russia's now-discredited drug testing lab, as telling him that the state's Federal Security Service officers "tried to control every single step of the anti-doping process in Sochi".

Hosts Russia won 13 gold medals at the Sochi Winter Olympics.

A brief preview of the interview released by CBS reveals no names of suspected dope cheats. But the story could signal a widening of the doping scandal that has engulfed Russian athletics, with the country's track and field stars facing a ban from the 2016 Rio Olympics in August.

Stepanov and his wife, banned athlete Yuliya Stepanova, appeared in a German television documentary claiming systematic doping in Russian athletics in 2014.

The allegations were later supported by an investigation by a World Anti-Doping Agency independent commission which found evidence of "state-sponsored" doping and widespread corruption.