The Kremlin's spokesman said Wednesday that Russia rejects a US investigation into alleged abuse of performance-enhancing drugs by Russian athletes.
Russia treats cases where US courts are operating beyond their jurisdiction "with a notable degree of incomprehension and rejection," spokesman Dmitry Peskov told state news agency TASS.
However, Russia is ready to assist international authorities in investigating individual allegations of doping, Peskov added.
Russia's Sport Ministry has vowed to comply fully with the World Anti-Doping Agency's investigation, the Interfax news agency reported earlier in the day.
The ministry said it supports the WADA's investigation, but doping allegations should be made against individual athletes, not the country in general, according to the report.
"Clean athletes who have spent years training honestly and observing all the rules and regulations, including against doping, should not lose their right to participate in competitions," the ministry was quoted as saying.
Russia was suspended from international competition in November after a damning report on doping by the WADA.
The International Olympic Committee (IOC) said Tuesday that 31 athletes have tested positive for doping in the retesting of samples from the 2008 Beijing Games.
Disciplinary proceedings against the undisclosed athletes from 12 countries and six sports have been opened, the IOC said.
Russia Sports Minister Vitaly Mutko told TASS on Wednesday that "the statement from the IOC shows that this is not a problem with Russia only."
The New York Times reported on Tuesday that US federal authorities were investigating allegations of state-led doping by top Russian athletes, on grounds of fraud and conspiracy.
The US investigation is reportedly being conducted by the office of the US attorney for New York's Eastern District, the same prosecutors who last year indicted top officials from football governing body FIFA on corruption charges.
Among the dozens of athletes, coaches and officials targeted in the US doping probe is Grigory Rodchenkov, former chief of Russia's anti-doping laboratory, according to the newspaper.
In a recently published interview, he told the Times that Moscow for years had ordered him to assist Russian athletes in evading bans on the use of performance-enhancing drugs.