Russia's Sports Minister Vitaly Mutko has revealed that "around 3,000" samples have recently been taken from athletes by officials investigating allegations of widespread, systematised doping in the country.
The claims were aired earlier this month in a series of documentaries broadcast by German broadcaster ARD, and now the World Anti-Doping Agency (WADA) taken steps to establish their validity.
Mutko confirmed a WADA Commission, including their director of science Olivier Rabin, had now visited the country at his request.
"They took around 3,000 samples to be checked in laboratories," he told the sports agency R-Spor.
"I wrote a letter to WADA, in which I said very precisely that we were open to receiving any commission and ready to show everything.
"A Commission from WADA has already been to visit us, which included three people who were led by the director of science.
"We will continue to work along this route and we are completely open."
Earlier this month, WADA announced its former President Richard Pound would head a special Commission looking into the documentary's claims, with work due to start on January 1.
Allegations of widespread doping were strongly denied by Russia's AthleticsFederation, whose President Valentin Balakhnichev, denounced many of its claims as "lies".
Balakhnichev has since stood down from his role as International Association of Athletics Federations treasurer while the allegations are investigated.
Vladimir Kazarin, the coach highlighted as a main offender in the documentary, has claimed he was suing the programme-maker Hajo Seppelt.
Kazarin also claims he is filing lawsuits against Russian middle-distance runner Yulia Stepanova and her husband Vitaly Stepanov, a former Russian Anti-Doping Agency official whose claims were at the centre of the programme's claims.
Stepanova, a former 800m World Championship finalist under her maiden name Rusanova, is currently serving a two-year doping ban.
"Together with the Russian Athletics Federation, we will be filing law suits against Yulia Stepanova, her husband Vitaly as well as against the director of the film Hajo Seppelt," the 62-year-old Kazarin said.
"This documentary came about due to clever editing.
"I did not give anyone banned substances.
"It is a really strange situation:
"Yulia was disqualified for doping offences and at the same time says she wants the sport to be clean."
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