Former Australian cricket captain Steve Waugh has said Ian Thorpe is the last sportsman he could ever imagine failing a doping test.

"If there is one person I would assume is clean then it would be Ian Thorpe," said Waugh, who went to the same school as the Australian swimmer some 15 years before him.

"I think he was tested all through his career three times or two times a week. He was at East Hills High School the same as me so I'm backing him," he told reporters in Barcelona where he was attending the Laureus sports awards on Monday.

"I know him pretty well and I couldn't believe in any way that he'd be involved in that."

Details of a test taken by Thorpe last May that showed elevated levels of naturally-occurring hormones were leaked to French newspaper L'Equipe.

Swimming and doping officials have confirmed Thorpe did not fail the test and there was no suggestion of any wrongdoing but the retired Olympic champion has said his reputation had already been tarnished.

"I'd be totally shocked if anything was untoward," said Waugh. "Look, he's been a champion since he was 14. I assume he wasn't taking anything at 14 so why would he take anything at 20? It doesn't make sense.

"It is one of those things that has come out of left field ... It's a shame for him. He has worked so hard, broken so many world records and won so many gold medals and then this comes up."

Swimming's world governing body FINA has promised to carry out a full investigation into how details of the test results were leaked, while the World Anti-Doping Agency (WADA) has expressed its concern at the serious breach of confidentiality.