French sports newspaper L'Equipe claimed on its website Friday that Thorpe, who retired from swimming in November, provided a sample last May that showed abnormally high readings for testosterone and luteinizing hormone.

Neither FINA nor Swimming Australia would Saturday confirm the athlete's identity as being Thorpe, however world swimming's governing body did not deny the report that named the retired 24-year-old superstar.

FINA did confirm it has lodged an appeal with the Court of Arbitration for Sport on a doping test, saying it was seeking clarification of the adverse analysis.

The news has rocked the swimming world with Thorpe recognised as a prominent campaigner against the use of performance-enhancing drugs in the sport.

"He is a young man of unbelievably strong principles and integrity and I've known him for a long time so I will support Ian 1000 percent," Swimming Australia chief executive Glenn Tasker said.

"At this very minute there isn't a positive test, it's an adverse finding.

"Hopefully reasonably-thinking people will accept that for what it is and there won't be hanging anyone until the judge has made his decision."

Australian Prime Minister John Howard said Thorpe's reputation should not be damaged unless he is proven guilty.

"As far as I'm concerned, until solid evidence of the contrary is produced Ian Thorpe remains a great Australian champion," said Howard.

Dutch head coach Jacco Verhaeren, the mentor for Thorpe's greatest Olympic rival Pieter van den Hoogenband, said he was dismayed that the Australian's career was being tainted by allegations that could prove baseless.

"This is damaging somebody's career without any reason and I think that's the worst about it," Verhaeren said at the world championships here.

"The media should be very careful with this kind of information ... if it's from his own body there is no problem so there is also no use to write about it.

"I think there are people to investigate these kinds of things and I think we should first listen to these people before damaging somebody who is an exceptional sportsman and to me a very honest guy and to me he is not under suspicion."

Canadian head coach Pierre Lafontaine said he was disgusted the allegations had been raised during the world championships.

"I find it astonishing that it's done at this time," said Lafontaine.

"I just think it's ridiculous ... why is it done in the middle of this meet when we are in the middle of a celebration of swimming all around the world.

"I can only tell you that (Thorpe) has been a great ambassador for sports all around the world and I would be very surprised (if it were true)."