Russian President Vladimir Putin has ordered an investigation into claims the country's athletes have been part of a systematic doping programme.
Putin was speaking for the first time since a World Anti-Doping Agency (Wada) independent commission revealed its damning findings on Monday.
He said he wanted "professional co-operation" with anti-doping bodies.
"The battle must be open," said Putin. "A sporting contest is only interesting when it is honest."
Russian Sports Minister Vitaly Mutko had earlier said Britain's anti-doping system had "zero value" and was "even worse" than Russia's.
That accusation was rejected by the Department for Culture, Media and Sport.