Winfrey initially supported Frey - making a surprise phone call to Larry King Live to back her author when he was being interviewed by CNN. But yesterday she brought him on to her show and in front of baying, booing live audience, introduced the author as "Mr Bravado Tough Guy", before taking him to task for a string of inaccuracies. "I really feel duped," she said. "But more importantly, I feel that you betrayed millions of readers."

Frey, who submitted his book as fiction but eventually had it published as a memoir without a word being changed, defended his work. "I don’t think it is a novel," he said. "I still think it’s a memoir." But after Winfrey had addressed a series of disputed passages, including Frey's claim to have endured root canal surgery without anaesthetic, the author was more contrite.

"This hasn’t been a great day for me," he said. "I feel like I came here and I have been honest with you. I have, you know, essentially admitted to..." "Lying," Winfrey interrupted. "To lying," said Frey. "It’s not an easy thing to do in front of an audience full of people and a lot of others watching on TV... If I come out of this experience with anything it’s being a better person and learning from my mistakes and making sure I don’t repeat them."

Winfrey said she had received hundreds of messages of support for Frey when the first doubts were expressed about his memoir. But she said these had clouded her judgment, leading her to defend him on CNN, saying the controversy was "much ado about nothing". "I regret that phone call," she said yesterday. "I made a mistake. I left the impression that the truth does not matter, and I am deeply sorry about that. That is not what I believe... To everyone who has challenged my position, you are absolutely right."