Berlin, April 21 (IANS/DPA): German Minister of the Interior Nancy Faeser has called for a rigorous investigation after reports that 23 Chinese swimmers failed doping tests ahead of the Tokyo 2021 Olympics, where several of them competed after all were cleared.

Faeser, who's also responsible for sports, told dpa on Sunday that the reports have shaken confidence in the World Anti-Doping Agency (WADA) and the global fight against cheating in elite sport.

"Just a few months before the Olympic Games, the suspicion the case was ignored or even covered up must be fully investigated as quickly as possible. If there's such a serious suspicion of doping, then it must be independently investigated by WADA," Faeser said.

"If confirmed that Chinese swimmers were able to become Olympic champions in Tokyo despite previous evidence of doping, that would be a disaster for world sport," she added. "This case is a slap in the face of all innocent and honest athletes."

German broadcasters ARD, the New York Times and Australian paper Daily Telegraph reported on Saturday that the swimming governing body World Aquatics, then FINA, and WADA were satisfied with the Chinese explanation that contaminated food had led to the positive tests.

ARD Sportschau said that its investigation together with the New York Times revealed that the swimmers tested positive for the banned heart medication trimetazidine (TMZ) at a domestic competition in Shijiazhuang in early 2021.

No sanctions were imposed because the positive tests were deemed to come from contamination after China said its investigators found traces of TMZ in various areas of the kitchen were the meals for the athletes had been prepared.

The swimmers were cleared to continue competing in June 2021 and the case never became public. A 30-strong Chinese team, including 13 of the 23 with positive tests, went on to win six medals in Tokyo, including three gold medals.