United States swimming coach John Leonard has insinuated that China's gold medallist Ye Shiwen is taking performance-enhancing drugs.
Ye took the gold in the women's 400m individual medley with a world record time of 4:28.43, a feat that Leonard described as "suspicious".
He told The Guardian: "The one thing I will say is that history in our sport will tell you that every time we see something, and I will put quotation marks around this, 'unbelievable', history shows us that it turns out later on there was doping involved."
The executive director of the World Swimming Coaches Association compared Ye's performance to the East German women swimmers in the 1980s, who were found to be doping.
"Any time someone has looked like superwoman in the history of our sport they have later been found guilty of doping," he added. "I have been around swimming for four-and-a-half decades now.
"If you have been around swimming you know when something has been done that just isn't right. I have heard commentators saying 'well she is 16, and at that age amazing things happen'. Well yes, but not that amazing. I am sorry."
Ye, who also set a new Olympic record in the 200m individual medley, is in back in action in the final this evening.
