A New York Times investigation found several Chinese swimmers tested positive for banned substance Trimetazidine before the 2020 Tokyo Olympics.

China and the World Anti-Doping Agency allowed these athletes to compete despite the positive tests.

Chinese swimmer Zhang Yufei won four medals, including two golds, after testing positive for the substance.

Two male Chinese swimmers also tested positive; one won gold and the other set a world record.

Germany's Interior Minister Nancy Faeser has demanded a full inquiry into the potential doping cover-up.

The controversy has fueled concerns over the integrity of competition and may impact the upcoming Paris Olympics.