The World Anti-Doping Agency has said Russian hackers stole confidential medical profiles about US Olympic athletes and posted them online. The Russian government denies any involvement in the cyber attacks. Russia completely ruled out any involvement in the hacking attack on the World Anti-Doping Agency's database. The Kremlin's spokesperson said on Wednesday "there is no involvement of the official Moscow, government or special services in such actions." He went on to say such "unfounded allegations do not honor any organization.

On Tuesday WADA claimed that its servers had been attacked by hackers and that sensitive information about several prominent American athletes' drug use was stolen. The Agency said it was informed by law enforcement authorities that the attacks originated from Russia.

In its statement WADA said the cyberattack was conducted by an espionage group called the Tsar Team, also known as "Fancy Bear."

Though Western security experts say they suspect the group is tied to Russian government, Moscow has strongly denied any links. Fancy Bear itself says it's an anonymous hacker group representing an international team.

The WADA leak included the personal medical profiles of such celebrity athletes as U.S. tennis sisters Serena and Venus Williams and 4-time Rio Olympic gold medalist Simone Biles. According to the leaked information, these and some other athletes used banned drugs for therapeutic purposes and were given waivers to do so.

The International Olympic Committee confirmed in a statement that the athletes did not violate any anti-doping rules during the Olympic Games and condemned the attack as an attempt to "tarnish the reputation of clean athletes".