LONDON, England (AFP) — American swimming great Michael Phelps yesterday defended Chinese prodigy Ye Shiwen and said it was "sad" that her Olympic performances had been greeted with scepticism.

Phelps, who retired in London with a record haul of 22 medals, including 18 gold, said 16-year-old Ye had simply worked hard to achieve her two Olympic titles, one set in world-record time.

"It's kind of sad that people have a great swim and that's the first thing they say," Phelps said in an interview with CNN.

"People who work hard — it shows. There are people who just jump to that conclusion sometimes, and it's not right."

Ye's 400m individual medley world record, whose final lap was quicker than US winner Ryan Lochte in the men's final, was described as "impossible" by American coach John Leonard, and also questioned by British media.

Ye flatly denied doping, and her teammate Sun Yang was also angered by the speculation.

"It is all down to training and hard work that we have results," he said. "Chinese are not weaker than those in other countries."

Phelps added that he had been pleased to see Ye swim. "Being able to watch her was pretty amazing," he said.