'One and done'

In the wake of a scandal involving Chinese swimmers, Olympic great Michael Phelps doubled down on his support for tougher sanctions - including a lifetime ban - for anyone who tests positive for a banned substance.

"If you test positive, you should never be allowed to come back and compete again," said Phelps, who is at the Paris Games. "I believe one and done."

The World Anti-Doping Agency and World Aquatics have acknowledged that 23 Chinese swimmers tested positive for a banned substance ahead of the Tokyo Olympics. The results were not made public until media reports surfaced this year, with both organizations accepting the Chinese explanation that the positive tests were caused by tainted food.

Nine of those swimmers won medals - several as part of relay teams - in Paris, prompting British star Adam Peaty to gripe that the playing field was not even.

Phelps said the Chinese swimmers who tested positive should not have been allowed to compete in Tokyo or Paris.

"If everybody is not going through that same testing, I have a serious problem because it means the level of sport is not fair and it's not even," he said.

When Phelps was setting multiple world records and becoming the most successful Olympian in history, he knew there were plenty of people who wondered if he could be pulling off such feats without a pharmaceutical boost.

Phelps said he actually subjected himself to extra testing in the leadup to the 2008 Beijing Olympics - where he broke Mark Spitz's iconic record with eight gold medals - to alleviate any doubts he was racing clean.

"People called me a cheater throughout my career," he said. "I subjected myself to do more testing - blood and urine - weekly. Why? For the reason that I could say I'm not cheating and I am clean and here are the results.

"I did it the clean way," he added. "I won 23 Olympic gold medals the clean way. It can be done."

Phelps said he always felt like some competitors were doping during his five Olympics, "but that's out of my control."

"Everybody has to come together and figure out one way to test everybody all over the world," Phelps said. "And if you test positive, you should never be allowed to come back and compete again."

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