Tyler Hamilton, a former teammate of Lance Armstrong, told "60 Minutes" that he used performance-enhancing drugs with the seven-time Tour de France winner to cheat in cycling races, including the tour.
Hamilton says Armstrong took a blood-booster called EPO in the 1999 Tour and before the race in 2000 and 2001. Armstrong won the race every year from 1999-2005.
The interview with Hamilton was broadcast on the "CBS Evening News" on Thursday.
"I saw (EPO) in his refrigerator. ... I saw him inject it more than one time," Hamilton said, "like we all did. Like I did, many, many times."
Hamilton told "60 Minutes" reporter Scott Pelley: "(Armstrong) took what we all took ... the majority of the peloton," referring to riders in the race. "There was EPO ... testosterone ... a blood transfusion."
EPO is a drug that boosts endurance by increasing the number of red blood cells in the body.
Armstrong has steadfastly denied doping and has never failed a drug test. However, federal authorities are investigating whether Armstrong and his former U.S. Postal team did participate in a systematic doping program.
Hamilton's accusations come a year after Floyd Landis, another former Armstrong teammate, made similar allegations of drug use by Armstrong and the team. And like Landis, Hamilton said Armstrong failed a drug test at the 2001 Tour de Suisse.
Armstrong's attorney Mark Fabiani dismissed the "60 Minutes" report.
"Hamilton is actively seeking to make money by writing a book, and now he has completely changed the story he has always told before so that he could get himself on '60 Minutes' and increase his chances with publishers," Fabiani said in a statement. "But greed and a hunger for publicity cannot change the facts: Lance Armstrong is the most tested athlete in the history of sports: He has passed nearly 500 tests over twenty years of competition."
Shortly after Hamilton's comments aired, Armstrong launched a website that refuted the claims and tweeted: "20+ year career. 500 drug controls worldwide, in and out of competition. Never a failed test. I rest my case."
Hamilton won a cycling gold medal at the 2004 Athens Games but failed a drug test later. He was allowed to keep his medal, however, because problems at a laboratory meant his backup 'B' sample could not be tested.
Hamilton returned to racing and won the 2008 U.S. road championship, but retired last spring after admitting he took an antidepressant that contained the banned steroid DHEA. He was officially banned from cycling for eight years.
On Thursday, ESPN reported that Hamilton sent a letter to friends apologizing for lying about his past drug use. He said he testified six hours before the Los Angeles grand jury investigating Armstrong.
Landis was stripped of his 2006 Tour de France title after testing positive for taking synthetic testosterone. He denied taking performance-enhancing drugs for years before admitting he doped for much of his career.
Asked to comment on Hamilton's interview, Landis said in an email to The Associated Press: "The only comment I have is that I wish the best for Tyler."
The "60 Minutes" segment, which will air in its entirety Sunday at 7 p.m. Eastern, also includes an interview with another former Armstrong teammate, Frankie Andreu.
Now one of the race directors at the Tour of California, Andreu told Pelley he took banned substances because lesser riders he believed were doping were passing him. "Training alone wasn't doing it and I think that's how ... many of the other riders during that era felt, I mean, you kind of didn't have a choice," he is quoted as saying.
Andreu's wife, Betsy, who has said Armstrong discussed taking performance-enhancing drugs as doctors prepared him for cancer treatment in 1996, said she and her husband are working with investigators.
"We are cooperating, and we'll just tell the truth. And telling the truth has been costly," she said. "It's not popular to tell the truth about Lance."
Andreu and Hamilton were both in on the ground floor of Armstrong's record-breaking Tour de France domination, and were among the key cyclists he relied on and lived with as he put his grip on the three-week race.
They both rode with Armstrong for the first two Tours that he won, in 1999 and 2000, all together under U.S. Postal colors. Hamilton rode with Armstrong on his 2001 Tour win for U.S. Postal, too.
Andreu's Tour links with Armstrong also predate the start of his winning streak. Andreu and Armstrong were teamed together at Motorola for the 1993, '94, '95 and '96 Tours.
In his biography, "It's Not About the Bike," Armstrong described Andreu on that first winning Tour in 1999 as "a big powerful sprinter and our captain, an accomplished veteran who had known me since I was a teenager."
Hamilton was a climber, and one of his jobs was to help haul Armstrong up the Tour's punishing climbs.
Recently, American investigators reached out to their colleagues in France with an evidence request that specifically targets U.S. Postal and mentions Armstrong by name, according to those who have seen it.
The Americans requested urine samples that were taken from U.S. Postal riders for anti-doping controls and were subsequently frozen and stored by France's anti-doping agency. The requested samples included those from the 1999 Tour.
French authorities also have been asked to interview and take witness statements from people there who were connected to U.S. Postal or who worked in French anti-doping while Armstrong dominated cycling's glamour race.