PARIS In the wake of a Chinese doping scandal, Michael Phelps doubled down Monday 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, cut and dry, Phelps said. 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 bodies 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, leading British star Adam Peaty to gripe that the playing field was not even.

Phelps reiterated those sentiments, saying the Chinese swimmers who tested positive should not have been allowed to compete in either Tokyo or Paris.

Or anywhere else, for that matter.

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 its not even, he said. If youre taking that risk, then you dont belong in here.