A row has broken out between the United States and China over a record-breaking Olympic swim, with suggestions of performance-enhancing drugs being used.
A leading American coach says Ye Shiwen's gold-winning performance in the 400m individual medley defies belief.
John Leonard said Ye's performance was unbelievable and disturbing and called for an investigation into the Chinese, even hinting at the use of genetic manipulation, Radio New Zealand's London correspondent reports.
Ye Shiwen, 16, took several seconds off her personal best on Saturday and swam faster than the American winner of the men's race Ryan Lochte in the last 50m of the event.
Ye has denied taking performance enhancing drugs, attributing her success to hard work and training.
There is no evidence against her and all Olympic medal winners are automatically tested.
The head of the Chinese swimming team says Ye has been seen as a genius ever since she started swimming.
Britain's top Olympic official Colin Moynihan says she's been through the World Anti-Doping Agency's testing programme and she's clean.
The United States Olympic Committee has distanced itself from the suspicions voiced by John Leonard.