UPDATE 3-Anti-doping agency says athlete data stolen by Russian group
* Group targets U.S. athletes
* Russia says government was not involved
* IOC, USADA, ITF and USA Gymnastics condemn leaks (Adds that U.S. government investigating ties to Russian government, comment from Simone Biles)
By Alan Baldwin and Jim Finkle
Sept 13 (Reuters) - The World Anti-Doping Agency said on Tuesday that hackers stole confidential medical information about U.S. Olympic athletes and published it on the internet, blaming a Russian group for the attack.
The U.S. 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 authorized 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 U.S. cyber-security researchers. Continuación...