A row over the surprising performance of Chinese Olympic swimmer Ye Shiwen has descended into a diplomatic tit-for-tat between as Beijing officials attempt to point the finger at US medal magnet Michael Phelps.
China's former Olympic doctor and the country's head of anti-doping both dragged US swimmer Phelps into the row on Tuesday, claiming no one had ever questioned his word records or 17 Olympic gold medals.
Their comments come a day after American coach John Leonard described the world record swim by 16-year-old Ye Shiwen, which was faster than men's champion Ryan Lochte in the final 100m, as "disturbing" and "suspicious".
Ye took gold in the 400m women's medley in a world record time of four minutes and 28.43secs. The swimmer denied she had ever used performance-enhancers. "My achievements derive from diligence and hard work, I will never use drugs. Chinese athletes are clean.
"The Chinese team is extremely strict on doping control, so I can assure you that is not an issue with us."
Dr Chen Zhanghao, one of China's former Olympic doctors, claimed he had always suspected US swimmer Phelps of using performance-enhancing drugs, but denied Ye would have been able to get past stringent Chinese anti-doping rules
Chen told the Sydney Morning Herald: "America's Phelps broke seven world records! Is he normal?
"I suspect Phelps, but without evidence, I have to recognise that we should be grounded in facts. The Americans have made many extraordinary performances but without evidence we have kept silent."
Dr Chen, who has admitted his own role in doping athletes before China cracked down on the practice in the 1990s, said: "Once caught, the athlete, coach and sometimes team manager are dismissed.
"Before these Olympics, the Chinese sports administration repeatedly stressed the importance of anti-doping. It has been raised to a question of state dignity."
He added: "The Americans are very bad, they do a lot of evil. But they don't talk about themselves."
He said Ye Shiwen was successful because she has rare talent.
China's head of anti-doping told state news agency Xinhua that the suggestions were "biased."
Jiang Zhixue, from China's General Administration of Sport, said: "I think it is not proper to single Chinese swimmers out once they produce good results.
"We never questioned Michael Phelps when he bagged eight gold medals in Beijing.
"The Chinese athletes, including the swimmers, have undergone nearly 100 drug tests since they arrived here.
Mr Leonard, the executive director of the World Swimming Coaches Association had previously told The Guardian: "We want to be very careful about calling it doping.
"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.
"She looks like superwoman. Any time someone has looked like superwoman in the history of our sport they have later been found guilty of doping."
Adrian Moorhouse, who won gold for GB at the Seoul Olympics, criticised the USA in the Evening Standard.
He said: “It is sour grapes. I think it’s quite insulting actually.”
Duncan Goodhew, Olympic Village Deputy Mayor, and a gold medallist in the men's 100 metres breaststroke in the 1980 Moscow Olympics, said competitors were innocent until proven guilty.
"There are always incredible improvements in any large sporting event such as the Olympic Games, and of course, in terms of that, innocent until proven guilty," he told ITV Daybreak.
"I think it is very destructive and very irresponsible of anybody to accuse people until they are proven guilty."
"Many were also tested by the international federations and the British anti-doping agency. I can tell you that so far there was not a single positive case."
The teenager took five seconds off her personal best and more than a second off the world record in the 400m individual medley, in a swim described as "insanely fast" by previous world record holder Stephanie Rice.
The Australian swimmer said she "wouldn't want to get into [any doping allegations] but a 58 is an insanely fast swim, but I know she's a good freestyle swimmer.
"I swam next to her at worlds in the 200 IM last year and she came home over the top of me in that freestyle leg and I'm not exactly a bad freestyler, so she's a gun in freestyle."
Arne Ljungqvist, the chairman of the International Olympic Committee's medical commission and a veteran anti-doping official, said there were currently no concerns about Ye's achievement.
"Should I have my suspicions I keep them for myself, first of all, and take any action, if so, in order to find out whether something is wrong or not.
"You ask me specifically about this particular swimming. I say no, I have not personally any reason other than to applaud what has happened, until I have further facts, if so."
Ye is up against GB's Hannah Miley in the 200m metre medley final on Tuesday night.