The US government is investigating the case because there is evidence that the hackers are linked to the Russian government, though details are still sketchy, according to two sources familiar with the probe who were not authorised to publicly discuss the matter.
Russian news agencies quoted Kremlin spokesman Dmitry Peskov as saying any possible Russian government or secret service participation in the hacking was out of the question.
An FBI representative said she had no immediate comment on the release of the medical information, which prompted gymnast Simone Biles to disclose that she has an attention deficit hyperactivity disorder, or ADHD.
Wada issued a statement attributing the attack to Tsar Team, a hacking group widely known as APT28 and Fancy Bear by US cyber-security researchers.
Fancy Bear is one of two hacking groups accused in June of hacking the Democratic National Committee’s computer network. CrowdStrike, a firm hired by the DNC to respond to those attacks, said in June that Fancy Bear was probably working on behalf of the Russian military.
Wada said that law enforcement had told it the attacks originated in Russia. Wada spokeswoman Maggie Durand declined to elaborate or say how the operation had been uncovered.
“Wada condemns these ongoing cyber-attacks that are being carried out in an attempt to undermine Wada and the global anti-doping system,” said Director General Olivier Niggli in a statement.