Russian hackers have been blamed for breaking into a World Anti-Doping Agency database and posting confidential medical data of some American athletes online.
WADA said Tuesday the attack - which targeted some female members of the United States team who competed at the Rio Olympics - was carried out by a “Russian cyber espionage group” called Fancy Bears.
The hackers revealed records of “Therapeutic Use Exemptions” (TUEs) which allow athletes to use substances that are banned unless there is a verified medical need.
USA Gymnastics confirmed that Spring gymnast Simone Biles, who won four gold medals and one bronze at Rio, was among those athletes targeted.
“Simone has filed the proper paperwork per USADA and WADA requirements, and there is no violation,” said Steve Penny, president of USA Gymnastics, in a statement. “The International Gymnastics Federation, the United States Olympic Committee and USADA have confirmed this. Simone and everyone at USA Gymnastics believe in the importance of a level playing field for all athletes.”
Biles tweeted: "I have ADHD and haev taken medicine for it since I was a kid. Please know, I believe in clean sport, have always followed the rules, and will continue to do so as fair play is critical to sport and is very important to me."
WADA previously warned of cyberattacks after investigators it appointed published reports into Russian state-sponsored doping.
“These criminal acts are greatly compromising the effort by the global anti-doping community to re-establish trust in Russia,” World Anti-Doping Agency director general Olivier Niggli said in a statement.
WADA said it “extended its investigation with the relevant law enforcement authorities.”
The International Olympic Committee said it “strongly condemns such methods which clearly aim at tarnishing the reputation of clean athletes.”
“The IOC can confirm however that the athletes mentioned did not violate any anti-doping rules during the Olympic Games Rio 2016,” the Olympic body said.
The top American anti-doping official said it was “unthinkable” to try to smear athletes who followed the rules and did nothing wrong.
“The cyber-bullying of innocent athletes being engaged in by these hackers is cowardly and despicable,” said Travis Tygart, CEO of the U.S. Anti-Doping Agency.
The president of the governing body of tennis cautioned against “unjustified conclusions” being drawn from exemptions it approved.
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