A Moscow laboratory used for the dope testing of athletes has stopped operating after its accreditation was suspended by the World Anti-Doping Agency, Nikita Kamaev, the head of the Russian anti-doping agency, said.
Kamaev, responding to allegations of widespread doping among Russian athletes, urged commentators to distinguish between the and Russia's anti-doping agency, which he said was acting "in full compliance with the demands of the WADA codex".
His comments are the latest in a string of defensive remarks by Russian officials, following a hard-hitting report commissioned by WADA, which alleged widespread doping by Russian athletes and official collusion in a cover-up.
Earlier, the Kremlin's spokesman, Dmitry Peskov, described the allegations as "quite groundless".
Kamaev said that there were question marks about the credibility of the sources used in the report because they included sports people who had themselves failed doping tests.
"When the words of a sportsman who has broken the rules several times, and has already been disqualified, carry more weight than ours, then questions arise," he said.
The report, published on Monday by WADA's independent commission, said the Russian athletics federation should be suspended from all competitions, including the 2016 Olympic Games in Brazil, citing what it called "systematic doping" and corruption.
The Russian athletics federation rejected claims that it oversaw "systematic" doping by athletes after calls for the country to be suspended from international competition.
He also said that Russia was on the path to cleaning up the sport, emphasising the broadly efficient activity of the agency he heads.
"There are problems, but the objective facts, based on statistics, show that the Russian anti-doping agency is quite effective," he said.
"The agency takes the highest number of sanctions against transgressors in the world."