The former head of Russia's anti-doping laboratory Grigory Rodchenkov and American filmmaker Bryan Fogel said in a letter to the International Olympic Committee they can prove the use of doping by Russian athletes during the Sochi Olympics, the Gazeta.ru news website reported Friday.
They called for another investigation into all doping tests performed on Russian athletes during the Olympic Games in Sochi in 2014 and to tighten current World Anti-Doping Agency (WADA) rules.
Rodchenkov and Fogel said in the letter that it is important that they both be present during any new checks of the Sochi tests and said that journalists from The New York Times should also be present, Gazeta.ru reported.
On Thursday, Rodchenko told The New York Times newspaper that dozens of Russian athletes including at least 15 medal winners, participated in a state-run doping program during the Sochi Olympics.
Shortly afterwards the International Olympic Committee asked WADA to launch an investigation into the report.