Lance Armstrong faces a series of interviews over his sordid past if he is to one day return to sporting competition.

The World Anti-Doping Agency (WADA) and International Cycling Union (UCI) have told Armstrong, whose interview by Oprah Winfrey is to be broadcast later this week, to share his information with the authorities.

Armstrong was stripped of his seven Tour de France titles by the UCI last year and banned for life after the United States Anti-Doping Agency (USADA) found he had been at the heart of "the most sophisticated, professionalised and successful doping programme that sport has ever seen".

The motives for an admission - revealed yesterday by Winfrey - are unclear, but the 41-year-old Texan, who retired from cycling for a second time in 2010, was competing in triathlons until he was banned last year.

Reacting to Winfrey's comments ahead of Thursday's broadcast of the first part of the interview, WADA director general David Howman said in a statement: "Only when Mr Armstrong makes a full confession under oath - and tells the anti-doping authorities all he knows about doping activities - can any legal and proper process for him to seek any reopening or reconsideration of his lifetime ban commence."

The UCI, cycling's world governing body, also urged Armstrong to co-operate with official channels and join the independent review it set up in the aftermath of the USADA report.

An admission of guilt opens up Armstrong to all manner of legal actions, but Winfrey believes he was "ready" to come clean, albeit his admission did not happen in the way she had expected.

Armstrong and Winfrey met in the disgraced cyclist's home city of Austin, Texas, to record the interview on Monday.

It was later revealed the interview between the pair will be broadcast over two nights - leading to suggestions of profiteering - and Winfrey commented on her experience interviewing the man labelled the single biggest cheat in sporting history.

"I feel that he answered the questions in a way that (suggested) he was ready," talk show host Winfrey told the CBS This Morning programme.

"I would say he did not come clean in the manner that I had expected. It was surprising to me."

The first part of the interview will be shown on the 'Oprah' show at 9pm local time on Thursday (2am GMT on Friday), with the second to follow 24 hours later.

Winfrey said she was "satisfied" with Armstrong's answers during her interview; indeed, she was "mesmerised and riveted" by some.

She described Armstrong as "emotional" during the interview, but added that he "certainly had prepared himself". As had she.

"I had prepared like it was a college exam and walked into the room with 112 questions" - Oprah Winfrey

"I had prepared like it was a college exam and walked into the room with 112 questions," she said.

"In a two-and-a-half-hour interview I asked most of those questions, or at least as many as I could."

It was reported last night that International Olympic Committee member Dick Pound had raised the prospect of imposing punitive measures against cycling, proposing it could be dropped from the Olympics for a period to provide the UCI with impetus to clean up the sport.

Such a decision would be a dramatic step, and would require strong support from the IOC, which has over 100 members.

Former WADA head Pound could not be reached for comment.