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 - n Paris, leading British star Adam Peaty to gripe that the playing field was not even.