The World Anti-Doping Agency (WADA) says Russian hackers tampered with some of the drug profiles they leaked in a bid to embarrass dozens of star Olympic athletes.
In a notice on its website on October 6, WADA said Olympic contenders from the United States, Germany, Britain, Poland, and Denmark whose exemptions from drug bans were leaked by the Fancy Bears hacking group should check the stolen data for inaccuracies.
Fancy Bears posted information about the exemptions granted to U.S. gymnast Simone Biles and U.S. tennis players Serena and Venus Williams, among others.
The agency said the effort to expose what Russian officials have called questionable "therapeutic use exemptions" was "a cheap shot at innocent athletes."
It said the leaks were carried out in retaliation for agency investigations that led to more than 100 Russian athletes being banned from Rio because of illegal drug use.
In their latest leak on October 6, Fancy Bears posted letters from U.S. sports officials that were said to show more than 200 U.S. athletes had authorization to use banned drugs.
WADA said the hackers gained access to the leaked information through an account created by Olympic authorities, which has since been secured.