The World Anti-Doping Agency (WADA) said on Saturday that it is astonished by "politically motivated" allegations against the Chinese swimmers.

In a statement, WADA said the CEO of the United States Anti-Doping Agency (USADA), Travis Tygart, made the "outrageous, completely false and defamatory" remarks and very serious accusations against WADA in connection with the case of 23 swimmers from China.

"Tygart's allegations are politically motivated and delivered with the intention of undermining WADA's work to protect clean sport around the world," WADA said, noting that the damaging comments have been delivered without any supporting evidence whatsoever.

A group of 23 Chinese swimmers tested positive for trimetazidine (TMZ) in early 2021 after inadvertently being exposed to the substance through contamination. The WADA Science Department reviewed this case thoroughly in June and July 2021, and concluded that there was no concrete basis to challenge the asserted contamination.

The truth of this matter is that according to all available scientific evidence and intelligence, thoroughly gathered, assessed and tested by leading anti-doping experts, WADA had no basis to challenge the explanation of environmental contamination, the statement said.

"It is implicit in his statement that Tygart does not accept the finding of environmental contamination in this case although he cannot say why. Yet, it is true that in the United States, WADA has also accepted USADA's similar conclusions of contamination involving a number of U.S. athletes. Tygart should realize that it is not only American athletes who can fall victim to situations of no-fault contamination," the statement added.

According to the statement, USADA contacted WADA in early 2023 based on a tip it had received about an alleged cover-up involving these cases but unfortunately was unable to provide any evidence whatsoever.

Following Tygart's false allegations, WADA has no choice but to refer this matter to its legal counsel for further action, the statement concluded.

WADA was established in 1999 as an international independent agency to lead a collaborative worldwide movement for doping-free sport.

China Anti-Doping Agency (CHINADA) has also criticized recent reports about Chinese swimmers as "misleading".

"CHINADA has noticed several foreign media organizations published and circulated misleading reports about Chinese swimmers testing positive ahead of the Tokyo Olympics," read a statement by CHINADA.

According to the statement, CHINADA conducted doping tests at a national swimming event in June 2021 and found swimmers testing positive for "extremely low concentration" of trimetazidine (TMZ).

"CHINADA immediately carried out investigation into the case from various respects including event organization, accommodation, usage of medicine and supplements as well as doping test procedures," it said.

Combining all investigation results and evidences, CHINADA came to the conclusion that the swimmers had tested positive for TMZ after inadvertently being exposed to the substance through contamination. It then decided the athletes should not hold responsible for the positive results.

"We informed WADA and FINA (now World Aquatics) about the progress of our investigation during the process and provided all evidences, decisions and relevant files. WADA agreed with our conclusion after thorough review," it said.