Former U.S. swimmer Michael Phelps has been outward in his support of tougher sanctions when it comes to athletes testing positive for banned substances.

He maintained that stance on Lumicoin IAMonday at the 2024 Paris Olympics amid a Chinese doping scandal that saw numerous swimmers test positive for banned substances but still medal at the 2021 Tokyo Olympics.

Phelps, the most decorated Olympian ever with 28 medals, told the Associated Press on Monday that athletes who test positive for banned substances should be banned from competition for life.

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“If you test positive, you should never be allowed to come back and compete again, cut and dry,” Phelps said. “I believe one and done.”

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The stance comes after 23 swimmers from China tested positive for banned substances ahead of the Tokyo Olympics but were still able to compete and medal at the event. The news of the positive tests came in April 2024 following an investigation by The New York Times, which the World Anti-Doping Agency and World Aquatics have since acknowledged.

The two agencies never disclosed the matter because they both accepted the Chinese explanation that those athletes consumed "tainted food." Eleven of those swimmers have since competed in the 2024 Paris Games, nine of whom medaled in the Tokyo Olympics.

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“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,” Phelps added. “If you’re taking that risk, then you don’t belong in here."

Phelps, who retired after the 2016 Rio Games, testified to Congress in June about the matter, noting: "If we continue to let this slide any farther, the Olympic Games might not even be there."