Russian Sports Minister Vitaly Mutko has revealed that a World Anti-Doping Agency (WADA) commission visited Moscow and took around 3,000 samples from local athletes for testing.
WADA took the samples as part of an investigation the authority is conducting in response to a German TV documentary that featured what it claimed was an undercover video of Russian athletes and coaches admitting to covering up positive tests.
"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," Mutko told the sports agency R-Sport.
"A commission from WADA has already been to visit us, which included three people who were led by the director of science. According to my information, they took around 3,000 samples to be checked in a laboratory in Cologne as well as other laboratories.
"We will continue to work along this route and we are completely open," the sports minister added.
The programme was aired in three parts by German channel ZDF/ARD with many of its claims denounced as "lies" by the head of Russia's Athletics Federation Valentin Balakhnichev.
Balakhnichev has since stood down from his role as International Association of Athletics Federations (IAAF) treasurer while the allegations are investigated.
On Tuesday, Vladimir Kazarin, the coach highlighted as a main offender in the documentary, said he was suing the programme-maker Hajo Seppelt.
Kazarin is also 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.