People magazine, a trusted conduit for Hollywood publicists, reported this week that Jenner, 65, would open up in a coming interview with ABC News.

"Bruce is transitioning to a woman," the celebrity news weekly quoted a source close to the family as saying, after weeks of tabloid speculation.

"He is finally happy and his family is accepting of what he's doing. He's in such a great space. That's why it's the perfect time to do something like this."

Jenner's 88-year-old mother Esther Jenner, who lives in Idaho, meanwhile told RadarOnline.com that she had "just learned" about her son's gender transition.

"I have never been more proud of Bruce for who he is, himself as a father, as an Olympian, a wonderful public speaker," she told the gossip website.