The World Anti-Doping Agency (WADA) on Monday rejected accusations of a cover-up during its investigation into Chinese swimmers testing positive for a prescription heart drug and said it would take "whatever action necessary" in response to the allegations.

Reports over the weekend that 23 Chinese swimmers tested positive for trimetazidine (TMZ) — which can enhance performance — ahead of the Tokyo Olympics in 2021 led to a strong attack from the head of the United States Anti-Doping Agency (USADA), Travis Tygart.

Tygart said that WADA and the Chinese anti-doping body had "secretly, until now, swept these positives under the carpet" and called the situation a "potential cover-up."