Bruce Jenner's mother has reportedly confirmed widespread speculation that the reality star is transitioning into a woman.

Speaking out about her son's altering appearance, Esther Jenner revealed that she was proud that he had taken the bold move.

"I just learned about [his transition], Bruce filled me in, and we had a very long, long, long talk about it," she is reported to have told Radar Online.

She added: "I have never been more proud of Bruce for who he is, himself as a father, as an Olympian, a wonderful public speaker. He instils enthusiasm in people. He's gifted.

"Right now I am more proud of him for what he's allowing himself to do. I am more proud of him now than when he stood on that podium and put that gold medal around his neck. He deserves all the respect.

"I support him whole-heartedly. I just love him like I always have."

Jenner has been the focus of sex-change rumours after he reportedly had his Adam's apple surgically reduced, a common procedure often undertaken by men seeking gender reassignment. He also allegedly started taking oestrogen and asked to be referred to as "Brigitte".

The 65-year-old reality star's step-daughter Kim Kardashian confirmed that he is on a "journey" on US television.

"I think everyone goes through things in life, and I think that story and what Bruce is going through, I think he'll share whenever the time is right. I feel like that's his journey to talk about," she told Entertainment Tonight.

While Jenner has refused to address the mounting transgender claims, People magazine recently reported that he has chosen to film his 'journey' in a docu-series for the E! Network.

"People has confirmed that Bruce Jenner has been quietly making a very personal change. The former Olympian will soon be living life as a female," the magazine reported.

In January, InTouch magazine attracted fierce criticism after it featured a doctored photo of the former athlete wearing lipstick, curled hair and a woman's green silk scarf on the cover, with the headline "My Life As A Woman".