Australian swimming coach Denis Cotterell has rejected allegations of orchestrated doping in Chinese swimming, saying the east Asian nation is adamant about clean sport.

Cotterell is working with China’s top swimmers in the lead-up to the Paris Olympics and previously coached 1,500 metres freestyle world record holder Sun Yang, who is now suspended for a doping offence.

The World Anti-Doping Agency (WADA) confirmed reports over the weekend that 23 Chinese swimmers tested positive for a banned drug before the Tokyo Olympics.

Wada said it had accepted China’s findings that the results were due to contamination and decided against appealing the matter, triggering criticism from top swimmers and the US anti-doping authority.

Cotterell told the Sydney Morning Herald he stood by his swimmers “100 per cent” and said any positive test results in Chinese swimming were not part of a state-run programme.

“I am happy to say I absolutely in support of my swimmers and dispute any suggestion of anything orchestrated,” Cotterell said.

“The suggestion that it’s systemic is so far from anything I have seen here the whole time,” he said.

“They are so adamant on having clean sport.

“It’s sad to see what this suggests or looks like. Its unfortunate for everyone. I feel for the athletes here because of how hard they work now to eliminate the tag that was garnered in the ’90s.”

Chinese swimming was engulfed in several doping scandals during the 1990s, with multiple athletes failing drug tests before and during major championships.

Leading coaches and swimmers criticised Wada and China’s anti-doping authority over the weekend and questioned why the 23 swimmers’ test results were not made public.

Cotterell said he understood if rival swimmers were upset and that the process could have been better handled.

“It unfortunately allows that doubt to come out and to surface. I can’t prove anything, I just know the truth,” he said.

However, he was also insistent that failed drug tests from contaminated food was a consistent risk in China.

“(Swimmers) are not allowed to eat outside anywhere. When they go on a plane, they can’t eat the food,” he added.

Media reports said the swimmers tested positive for trimetazidine (TMZ), which is found in heart medication, months before the Tokyo Games started in July, 2021.

Cotterell’s former swimmer Sun, a triple Olympic champion, served a three-month doping ban in 2014 for taking trimetazidine, which he said he took to treat a heart condition.

The ban was not made public until after it ended.

Sun, 32, is currently serving a four-year ban for a separate doping offence which is due to expire next month and ruled him out of China’s ongoing Olympic trials in Shenzhen.

Cotterell said he had turned down an invitation to coach Sun again and that it was “conclusive” the swimmer would not be selected for China’s Olympic team because he was not at the Shenzhen trials.