FINA, the world governing body for swimming, later confirmed in a statement that they have referred a doping case to the Court of Arbitration for Sport (CAS) but stopped short of citing Thorpe as the focus of the investigation.

Australian Prime Minister John Howard was among those who came out to give Thorpe his backing. "I don't intend to react to, let alone endorse, unsubstantiated allegations in a French newspaper, " Howard said.

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

Thorpe is Australia's most successful Olympian, having won five gold medals at the Sydney and Athens Games. He announced his retirement from the sport, aged just 24, in November 2006.