After years of public denials, Olympic champion Ian Thorpe has reportedly revealed that he is gay in an interview with veteran British journalist Michael Parkinson.

The 31-year-old has reportedly confirmed his sexuality during the exclusive interview, which will be broadcast on Network Ten tonight.

Already celebrity support for the winner of five Olympic gold swimming medals is flowing on social media.

“So happy and proud for @ianthorpe,” actor Magda Szubanski tweeted.

“Coming out in his own time on his own terms. Wish you all things good darling boy.”

Fellow Olympic swimmer Stephanie Rice tweeted: “Thorpie is and always will be a superstar in my eyes.”

I won’t remember #IanThorpe for being a Gay swimmer, I will remember him for being the greatest of swimmers. #Legend #NobodysBusinessButHis

— GemmaTognini (@GemmaTognini) July 12, 2014

One day people won’t have to come out. Love is love. Who cares? #IanThorpe #Equality

— K D (@Mr_Fanta_Pants) July 12, 2014

Much love #samelove #ianthorpe . We salute your bravery.

— QT Hotels & Resorts (@QTHotelsResorts) July 12, 2014

In the Parkinson interview, filmed last month, Thorpe also details his battles with depression and his public denial of his sexuality in his 2012 autobiography This Is Me, a media company reports.

Australian Marriage Equality national director Rodney Croome praised Thorpe for coming out.

“(It) has clearly been a difficult struggle for him and I hope Australians appreciate the trust and confidence he has placed in us all by revealing he is gay,” Mr Croome said.

“Nothing has changed about Ian Thorpe. He is still a great Olympian and a great Australian. But what needs to change is an unfair law that treats our greatest Olympic champion as a second class citizen.”

Mr Croome criticised the law denying gay Australians the right to marry.

Gay Times Magazine tweeted “big Love to @ianthorpe”.