Around 3,000 samples have been taken from Russian athletes by officials investigating claims of widespread doping in the country.
The World Anti-Doping Agency (Wada) launched its investigation following allegations made in a German television documentary.
Russian sports minister Vitaly Mutko confirmed a Wada commission had now visited the country at his request.
He said: "They took around 3,000 samples to be checked in laboratories."
Mutko told the sports agency R-Sport: "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."
Programmes aired by the German broadcaster ARD in December contained a number of allegations including one claim that as many as 99% of Russian athletes were doping.
There were also allegations of cover-ups from within Russian athletics, while the International Association of Athletics Federations (IAAF) came in for criticism.
It was claimed that a list of 150 suspicious blood samples, including one from a top British athlete, were not properly investigated by the sport's world governing body.
The allegations were denounced as "lies" by Russia's Athletics Federation, while the IAAF launched its own inquiry.
Earlier this month, Wada announced its former chief Dick Pound would head up an investigatory commission looking into the German documentary's claims but said it would not start work until 1 January.