A doping row involving Chinese athletes may prove to be a tinderbox at the Olympic swimming meet, where the United States faces the biggest challenge to their reign in decades.

Some of the world¡¯s best in the sport have criticized anti-doping authorities and raised concerns about the competition¡¯s integrity following revelations in April that 23 Chinese swimmers were allowed to compete at the Tokyo Games despite testing positive for the banned heart medication trimetazidine (TMZ).

The World Anti-Doping Agency accepted the findings of a Chinese investigation that the test results were due to contamination from a hotel kitchen the team was staying at.