Cyclist Lance Armstrong has reportedly confessed to using drugs during the recording of his interview with Oprah Winfrey.
USA Today said Armstrong did not confirm which drugs he used during the interview, which will be broadcast on Thursday. His lawyers have not responded to subsequent requests for comment.
Although US media had widely speculated that Armstrong would admit to cheating in the interview, neither Winfrey nor Armstrong have since confirmed today's report.
"We are not confirming any specific details regarding the interview at this time," a spokesman for Oprah's network OWN told Reuters.
Armstrong has always vehemently denied using performance-enhancing drugs.
CBS reported Armstrong had indicated he may be willing to testify against others involved in illegal doping and was in talks about repaying part of the taxpayer money he earned during his career.
Oprah, on Twitter, offered little more herself, other than to say Armstrong came prepared for the interview, which will be broadcast on Thursday.
Just wrapped with @lancearmstrongMore than 2 1/2 hours . He came READY!— Oprah Winfrey (@Oprah) January 14, 2013
The unconfirmed reports about his admissions followed confirmation that Armstrong apologised to the staff of the cancer foundation he started because of the damage he had caused.
"He had a private conversation with the staff, who have done the important work of the foundation for many years," said Livestrong Foundation spokeswoman Katherine McLane.
"It was a very sincere and heartfelt expression of regret over any stress that they've suffered over the course of the last few years as a result of the media attention," she said.
Shortly after, Armstrong joined his legal team to meet with Winfrey for an interview described in media publicity as "no-holds-barred".
The interview was supposed to take place at Armstrong's home in Texas but was switched to a hotel in downtown Austin after news crews camped outside his house before dawn.
But an October report from the US anti-doping body USADA cited Armstrong's involvement in what it characterised as the "most sophisticated, professionalized and successful doping program that sport has ever seen," involving anabolic steroids, human growth hormone, blood transfusions and other doping.
Less than two weeks later, Armstrong's seven Tour de France victories were nullified and he was banned from cycling for life after the International Cycling Union ratified the USADA's sanctions against him.