London: The World Anti-Doping Agency (WADA) will immediately probe recent statements made by Russian ex-doping official Vitaly Stepanov on the abuse of performance enhancing drugs in Russian sports, its chief Craig Reedie has said. Stepanov, a former employee of the Russian Anti-Doping Agency (RUSADA), stated in a 60-minute film aired by US TV channel CBS News last Sunday that at least four Russian gold medallists of the 2014 Winter Olympic Games were taking steroids, reports Tass. "WADA will probe these new allegations immediately," Reedie was quoted as saying on the WADA website on Tuesday. "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," Reedie added. Stepanov and his wife, Russian runner Yulia Stepanova, were at the centre of a series of documentaries on alleged doping in Russian sports aired by German TV Channel ARD in December 2014. The ARD's two-part documentary, entitled Geheimsache Doping (Secret Doping Case), claimed that Russian athletes systematically took banned substances on instructions from their coaches.