The World Anti-Doping Agency confirmed Tuesday that hackers accessed a database of confidential medical data and released the drug regimens of gymnast Simone Biles and three other top US Olympians. The agency went on to say the Russian government was behind the move.

The organization, which screens Olympic athletes for performance-enhancing substances, said the attack was carried out by "Fancy Bear," one of the same Russian government-sponsored hacking groups that security experts say broke into Democratic National Committee servers and made off with confidential documents. Fancy Bear members used a technique known as spear phishing to gain access to the Anti-Doping Administration and Management System (ADAMS) database through an account that was created by the International Olympic Committee, the agency said in a statement

"WADA has been informed by law enforcement authorities that these attacks are originating out of Russia," agency Director General Olivier Niggli said in the statement that also named Fancy Bear as the group. "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." The McLaren investigation refers to an inquiry into allegations of Russian government-sponsored doping at the 2014 Sochi Olympics. The investigation has been a major source of controversy between Russia and Olympics organizers.

The statement came shortly after the discovery of Fancy Bear, a site that published medical reports belonging to Biles; Elena Delle Donne, who led the US women's basketball team to a gold medal with a perfect 6–0 record; and Serena and Venus Williams, two former winning US Olympians in Tennis who were eliminated in the most recent Olympics games. The leaked documents appeared to show that all four US athletes tested positive for substances that are restricted by the International Olympic Committee but were given medical exemptions.

According to the documents, Biles tested positive for the psychostimulant methylphenidate and was also taking amphetamine. Donne, meanwhile, took hydrocortisone, while Serena Williams purportedly took oxycodone and hydromorphone, prednisone, prednisolone, and methylprednisolone, and her sister Venus used to take prednisone, prednisolone, triamcinolone, and formoterol. In a statement issued to Newsweek Olympics officials said none of the athletes singled out on the Fancy Bear website had broken any rules. Those rules grant exemptions for the therapeutic use of banned substances.

The Fancy Bear site used the documents to challenge the performance of US athletes, who won 46 gold, 37 silver, and 38 bronze medals, and the lack of impartiality of the International Olympic Committee. One section of the Fancy Bear site stated:

After detailed studying of the hacked WADA databases we figured out that dozens of American athletes had tested positive. The Rio Olympic medalists regularly used illicit strong drugs justified by certificates of approval for therapeutic use. In other words they just got their licenses for doping. This is other evidence that WADA and IOC's Medical and Scientific Department are corrupt and deceitful.

The site claimed the leaked data was only "the tip of the iceberg" and hinted that more leaks may follow.

The Fancy Bear leak continues a trend that started with the hack on the Democratic National Committee in which potentially sensitive data is leaked, presumably in an attempt to publicly discredit opponents. Tuesday's leak came after the majority of Russia's track and field team was banned from this year's Olympics following probes that found evidence of a government-run doping scheme that spanned years.

Some of the published DNC documents, for instance, led to the resignation of DNC Chair Debra Wasserman Schultz and has acted as a wedge to divide Democratic Party members. While Guccifer 2.0—the person taking credit for the DNC hack and the leaks that stemmed from it—claims to be a Romanian who acted alone, multiple security experts have found Russian fingerprints on much of the published data. Russian Prime Minister Vladimir Putin has denied Russian government involvement but has spoken in favor of the hacks.

Last month, WADA said that the ADAMS password for Russian runner Yuliya Stepanova was illegally obtained by a perpetrator who used it to access her account. Two years ago, she accused Russian athletes of engaging in large-scale doping fraud.

Post updated to add details in the fifth-to-last and third-to-last paragraphs about therapeutic use and Russian track and field team.