America's leading news agency, the Associated Press, reported on Monday night "a person said to be familiar with the situation" told it that Lance Armstrong had confessed to Oprah Winfrey during a pre-recorded interview that he used performance-enhancing drugs to win the Tour de France.

The person spoke on condition of anonymity because the interview is to be broadcast on Thursday on Winfrey's network. Winfrey is due to appear on "CBS This Morning" on Tuesday to discuss the interview with Armstrong.

Before the interview was taped, Armstrong took time out to apologise to the staff of his Livestrong cancer foundation. The disgraced cyclist, who was stripped of his seven Tour de France titles amid a welter of allegations that he was guilty of doping, addressed an emotional meeting of Livestrong staff and said "I'm sorry", an unnamed source told AP. Apologising for disappointing them and putting the foundation at risk, Armstrong reportedly "choked up" during the meeting, with employees also in tears.

Armstrong told staff he would try to restore Livestrong's reputation and encouraged them to continue supporting the charity's mission to help cancer patients and their families. The cyclist, a cancer survivor, founded Livestrong in 1997. He stepped down as a board member in November 2012 following the release of a damning report by the US Anti-Doping Agency that accused him of taking drugs.

The report alleged that Armstrong had masterminded the "most sophisticated, professional and successful doping program that sport has ever seen".

After the Livestrong meeting, Armstrong, his legal team and close advisers gathered at a downtown hotel in Austin, Texas, for the interview. Winfrey had earlier said she would film it at his home but the location changed after news crews staked out the cyclist's Spanish-style villa, hoping to catch a glimpse of Armstrong or the chat-show host. The interview is set to air at 2am on Friday UK time.

Armstrong has previously protested his innocence but is facing several legal challenges and has lost millions of dollars in sponsorship deals and endorsements. The Sunday Times is suing him for recovery of damages from a libel settlement after it accused him of doping.

Usada's sanctions against Armstrong were ratified by the International Cycling Union and he was banned from competitive cycling for life.