(CNN) -- It will take more than a television interview to reduce sanctions against Lance Armstrong, the World Anti-Doping Agency said Tuesday as Oprah Winfrey spoke out about her interview with the disgraced cyclist.
"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," agency Director General David Howman said.
Armstrong came "ready" for the interview Monday with Winfrey, the long-time TV talk show host said Tuesday. The interview will air in two parts, Thursday night and Friday night, on Winfrey's OWN cable network and the Internet, she said.
Speaking with her close friend Gayle King on "CBS This Morning," Winfrey would not give specific quotes from the interview. But she appeared to confirm multiple media reports that the former seven-time Tour de France champion used the occasion to acknowledge having used performance-enhancing drugs.
Asked whether she thought it was difficult for him to "come clean" to her, Winfrey responded, "Yes. I think the entire interview was difficult."
Word of what Armstrong apparently told Winfrey is accelerating calls by anti-doping agencies for the disgraced cyclist to come clean to them about all he knows.
The U.S. Anti-Doping Agency accused Armstrong in October of involvement in a sophisticated doping program while he was a professional cyclist. The world governing body for cycling, the International Cycling Union, stripped Armstrong of his seven Tour de France titles following the report. He's also been banned from the sport for life.
Winfrey said the former cyclist was forthcoming in the exhausting and intense interview taped Monday in Armstrong's hometown of Austin, Texas.
"We were mesmerized and riveted by some of his answers," she told CBS.
While the interview was revealing, Winfrey said, his demeanor surprised her. "He did not come clean in the manner that I expected." She didn't elaborate.
Winfrey said her team and Armstrong's camp had originally agreed not to leak details of the interview, and that she was surprised to find that not long after the interview, news reports were saying part of what Armstrong told her had "already been confirmed."
It was not immediately clear why Armstrong apparently chose to acknowledge doping after years of vigorous denials.
Juliet Macur, the New York Times reporter who broke the news on January 4 that Armstrong was considering an admission of doping, said he is too driven to accept life without sports.
"He has had (several months) to think about how he is lonely, how he doesn't have the adulation of fans at the finish line and nobody to beat right now," she said. "And it's driving him nuts."
Armstrong has been seeking to participate in triathlons sanctioned by U.S. Olympic authorities. Armstrong excelled at triathlons as a teenager and went back to the sport after retiring from cycling. He has been banned from officially sanctioned events.
Paul Willerton, who raced with Armstrong in the early 1990s, said any confession would be "just a starting point" for the cycling star.
"There are a lot of people still lying," Willerton said, naming former Armstrong consultant Dr. Michele Ferrari, and Johan Bruyneel, the one-time director of Armstrong's U.S. Postal Service team. "These guys are still perpetrating the lies and deception that Lance ruled over, and Lance holds the keys. He wants his control back, and he desperately wants to be liked by the American public. And you can't have it all."
The USADA suspended Ferrari for life in July, naming him as part of a large-scale doping conspiracy. Bruyneel is battling similar charges by the agency and said in October that he was "stunned" its findings on Armstrong revealed details of the allegations against him.
Meanwhile, fallout continued over legal wrangling concerning doping and Armstrong's involvement in the Postal Service team.
The New York Times had reported that Armstrong was planning to testify against several powerful people in the sport of cycling who may have facilitated doping. The newspaper, citing one person close to the situation, also said he was planning to testify against officials from the International Cycling Union.
A source with knowledge of the situation denied the reports.
Then there is a whistleblower lawsuit filed in 2010 by Floyd Landis, a former U.S. Postal rider. In the suit Landis accuses the team's former management of defrauding the government of millions of dollrs because the team management knew about the drug use and didn't do anything.
A source familiar with the matter confirmed to CNN that lawyers for Armstrong are in discussions with the Justice Department regarding the case. The government has until Thursday to intervene, not intervene or ask for an extension, the source said.
The Justice Department declined Tuesday to comment on potential civil action against Armstrong, saying the whistleblower suit is under court seal.
A spokesman for the U.S. Postal Service told CNN it could not discuss any of the legal issues associated with Armstrong and their prior relationship.
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CNN's Kevin Bohn contributed to this report.