Australia's teenage champion Ian Thorpe has volunteered to release the results of his next drugs test to erase any doubts about his swimming records.

The 17-year-old said he had asked the Australian Sports Drug Agency to release his sample results to prove he was clean ahead of the Sydney Olympics.

Thorpe's unusual offer came after German swim team captain Chris-Carol Bremer suggested in the Die Welt newspaper that Thorpe's size 17 feet could be the result of using banned human growth hormones.

Earlier this year, German coach Manfred Thiesman caused a storm by suggesting drugs could be behind the teenager's world record breaking performances.

"He's totally discarded the accusation," said Thorpe's manager David Flaskas. "He might have big feet, but the Germans have the big mouths."

Although a test for human growth hormones is yet to be scientifically validated, Thorpe has also vowed to give blood to be frozen for future testing to prove that he's clean.

"Until we have efficient drug testing systems those accusations are going to be made and that's why Ian's so strong about bringing in compulsory sophisticated blood testing criteria," Flaskas said.

Flaskas said the publicity would not affect the swimmer's Olympic preparations. "Every time they accuse him he goes quicker. So we'd be happy if they made another accusation a day before the 400 (metre event)."

Thorpe's father Ken said his son's big feet were merely hereditary. "You only have to look at his mother and father to understand where he got his build from. I know Ian's clean and I wouldn't advocate drugs in any way."

His mother also jumped to his defence, calling his German accusers "envious".

"From a very, very young age, I couldn't find booties to fit him. Big feet run in the family."

Australian sports medicine expert Peter Larkins said that while over-sized feet and hands may be a by-product of human growth hormone use, there were other, more obvious signs.

"Large jaws and foreheads are often associated with the use of human growth hormone," he said. Thorpe has clocked six individual world records in the past two years and is favourite for the 200 metres and 400 metres freestyle gold medals at the Sydney Olympics in September.

Meanwhile, the Chinese world record holder in the women's 200 metre individual medley, Wu Yanyan has tested positive for banned substances and will not be allowed to participate in the Sydney Olympic Games, swimming officials said yesterday.

Wu tested positive for an unknown substance following last May's Olympic Trials in Jinan city, in the eastern province of Shandong.

The tests were run by China's own sports doping authorities.