Russia's former anti-doping chief has accused the World Anti-Doping Agency, or WADA, of holding double standards against Russia, saying that it is unacceptable.

The comments came after a Russian hacking group known as Fancy Bears hacked into the WADA database. Medical information shows many athletes from western countries took substances that are banned by WADA. Athletes are allowed to use some medicines after they receive therapeutic-use exemptions from WADA.

However, according to a Russian lawyer, some 400 out of more than 600 applications from US athletes were approved by WADA in 2015. While the ratio for Russia was only 20 out of 54.

"When we saw the medication the US had been using on its athletes, we knew that they had broken the rules. It may seem like the medicine was for therapeutic use, but they are actually not for sports, and can be replaced by other types of  medicine," said NIkolay Durmanov, Fmr. head, Russian Anti-Doping Agency.

"The reason why fewer Russian athletes received therapeutic-use exemptions is that some Western countries have a prejudice against Russian athletes."