Lance Armstrong has been interviewed by Oprah Winfrey in Texas - and his comments apparently surprised the famed talk show host.

Washington - Lance Armstrong “came clean” to Oprah Winfrey on his use of performance-enhancing drugs, the talk show host said on Tuesday ahead of the much-awaited telecast of her interview with the disgraced cyclist.

Winfrey told CBS This Morning that her OWN cable network will broadcast the two-and-a-half-hour interview unedited over two nights from Thursday. Originally, a shorter broadcast was planned for one night only.

“I didn't get all the questions asked, but I think the most important questions and the answers that people around the world have been waiting to hear were answered,” Winfrey said.

“I can only say I was satisfied by the answers.”

The interview is Armstrong's first since he was stripped of his record seven Tour de France titles after the United States Anti-Doping Agency, in a 1 000-page report, put him at the heart of the greatest doping scandal in the annals of cycling.

For a decade he had vigorously denied using banned substances to win his way into the history books.

Prior to sitting down with Winfrey in a hotel suite in his hometown of Austin, Texas, on Monday, Armstrong, 41, went to the offices of Livestrong, the cancer charity he founded in 1997, and apologised in person to its staff.

“Lance came to the Livestrong Foundation's headquarters (and) offered a sincere and heartfelt apology for the stress they've endured because of him,” Livestrong spokesperson Rae Bazzarre told AFP.

Speaking from Chicago, Winfrey - when asked if Armstrong had “come clean” to her - said she and Armstrong had agreed at the outset not to talk about the content of the interview prior to its broadcast.

But a source in the Armstrong camp with knowledge of the interview confirmed to AFP that the Texan admitted to using banned substances in his career.

“And then, by the time I left Austin and landed in Chicago, you (the news media) all had already confirmed it,” Winfrey told CBS This Morning, a breakfast news programme.

“So I'm like, 'How did you all do that?' We all agreed that we weren't going to say anything.”

Winfrey, 58, said she went into “the biggest interview I've ever done” with 112 questions, and grilled Armstrong so intensely that, during a break at the 100-minute mark, Armstrong asked if their conversation might lighten up.

With a world-class scoop on her hands, Winfrey flew home to Chicago with the video tape in her handbag “along with my dog food” for fear it might be pilfered if beamed back to the editing room via satellite.

“I would say he did not come clean in the manner that I expected,” she added. “It was surprising to me. I would say that for myself, my team, all of us in the room, we were mesmerised and riveted by some of his answers.”

“I felt that he was thoughtful. I thought that he was serious... I would say that he met the moment.”

In Lausanne, Switzerland, cycling's world governing body, the International Cycling Union, called for Armstrong to give evidence to its ongoing investigation into widespread doping in the wake of his Winfrey interview.

Elsewhere, the South Australian state government said it would be “more than happy” for Armstrong to repay his appearance money from the Tour Down Under event, but it had no legal power to make him do so.

Armstrong took part in the event for three years running from 2009, raising cycling's profile and boosting participation by amateur riders. He was reportedly paid millions of dollars to appear. - Sapa-AFP