A woman walks into the head office of the World Anti-Doping Agency (WADA) in Montreal, Quebec, Canada November 9, 2015. [Photo/Agencies]

MOSCOW -- Moscow denied on Tuesday any involvement in the recent hacker attacks on the World Anti-Doping Agency (WADA) database.

"It can be definitely said that any involvement of Moscow, the Moscow government, and any Russian services in such actions is impossible," the Kremlin spokesman Dmitry Peskov told reporters.

Earlier in the day, a hacker group named Fancy Bears' claimed it had got access to the database of the world anti-doping body and figured out that "dozens of American athletes had tested positive," and the Rio Olympic medalists "got their licenses for doping".

Among those targeted are world top tennis players Williams sisters and US Olympic gold medal-winning gymnast Simone Biles.

"This is other evidence that WADA and IOC's Medical and Scientific Department are corrupt and deceitful," the hacker team said on its website.

Following the disclosure, the WADA confirmed the cyber attack in an online statement, saying that a Russian cyber espionage group was behind it, and it was conducted "illegally."