Twenty-three Chinese swimmers were given the OK to compete in the Tokyo Olympics in 2021 despite testing positive for trimetazidine, a banned heart medication.

The World Anti-Doping Agency said that the swimmers' tests had come up positive due to "inadvertently being exposed to the substance through contamination," a claim initially brought by the Chinese Doping Agency.

"Ultimately, we concluded that there was no concrete basis to challenge the asserted contamination," WADA’s senior director of science and medicine Olivier Rabin said in a news release.

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Swimming lane markers

General view of swimming lane markers at a pool. (Simon Bruty/Anychance/Getty Images)

The WADA said there had been "misleading information" that was spreading in the news, which led to their response.

The WADA said it had been given a tip by the U.S. Anti-Doping Agency as early as 2020 — before this case arose — about allegations of doping cover-ups in China but that USADA never followed up with evidence.

However, the WADA says they "reviewed this case thoroughly" and "concluded that there was no concrete basis to challenge the asserted contamination."

U.A. Anti-Doping Agency CEO Travis Tygart called the news of the Chinese positive tests "crushing."

"It’s even more devastating to learn the World Anti-Doping Agency and the Chinese Anti-Doping Agency secretly, until now, swept these positives under the carpet by failing to fairly and evenly follow the global rules that apply to everyone else in the world," Tygart said.

China swim team

China relay team celebrateing their victory in the women's 4x200m freestyle relay final during the Tokyo 2020 Olympic Summer Games at Tokyo Aquatics Centre.  (Rob Schumacher-USA TODAY Sports)

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But the WADA says it "followed all due process and diligently investigated every lead and line of inquiry in this matter."

"The information provided to us by USADA and others was reviewed on each occasion in line with our normal procedure, and assessed according to the criteria stipulated within our Confidential Source Policy," said Gunter Younger, the WADA's director of intelligence and investigations. "The data held by us clearly showed that there had been no attempt to hide the positive tests as they had been reported in the usual way by the Chinese authorities. Therefore, based on the available information and a lack of any credible evidence, the threshold for WADA I&I to open an investigation was not met."

China swim team after winning medal

China celebrating their gold medal during the medals ceremony for the women's 4x200m freestyle relay during the Tokyo 2020 Olympic Summer Games at Tokyo Aquatics Centre. 

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The 30-member Chinese swim team won six medals in Tokyo, including three golds. Many of the athletes still compete for China and are expected to swim at the Paris Olympics this summer.

The Associated Press contributed to this report.

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