Leading American athletes have hit back at the release of their medical records late on Tuesday, after a Russian cyber espionage group hacked a World Anti-Doping Agency (WADA) database at the Rio Olympics.
The group accessed confidential data from athletes such as tennis' Williams sisters and gold medal-winning US gymnast Simone Biles, before releasing it on their website.
Biles said on Twitter she had ADHD (attention deficit hyperactivity disorder) and has been taking medication since she was a child.
"Having ADHD, and taking medicine for it is nothing to be ashamed of, nothing that I'm afraid to let people know," she said.
"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."
The leaked information included medical exemptions which allow athletes to use normally forbidden substances - for example ADHD medicine.
"I was disappointed to learn today that my private, medical data has been compromised by hackers and published without my permission," Venus Williams said in a statement.
"I have followed the rules established under the Tennis Anti-Doping Programme in applying for, and being granted, 'therapeutic use exemptions.'"
"I am one of the strongest supporters of maintaining the highest level of integrity in competitive sport and I have been highly disciplined in following the guidelines set."
US basketball star Elena Delle Donne, another gold medallist from Rio, took to social media to post a picture of her recovery from thumb surgery and added a note relating to the hacking news.
"I'd like to thank the hackers for making the world aware that I legally take a prescription for a condition I've been diagnosed with, which WADA granted me an exemption for," she said. "Thanks, guys!"
WADA confirmed that a Russian cyber espionage group operator by the name of Tsar Team, also known as Fancy Bear, "illegally gained access" to WADA's Anti-Doping database via an International Olympic Committee-created account.
WADA said access was likely obtained by gaining possession of passwords through phishing of email accounts.
"WADA has been informed by law enforcement authorities that these attacks are originating out of Russia," WADA director general Olivier Niggli said.
"Let it be known that these criminal acts are greatly compromising the effort by the global anti-doping community to re-establish trust in Russia further to the outcomes of the Agency's independent McLaren Investigation Report."
WADA investigator Richard McLaren said in his report in July that Russia conducted a wide-ranging and state-sponsored doping programme.
As a result, all Russian athletes have been banned from the current Paralympics, while Russia escaped a blanket ban from last month's Olympics.
But its entire athletics team, apart from US-based long jumper Darya Klishina, was banned from the Rio Games in connection with two previous WADA reports.
