Tyler Hamilton used to pull Lance Armstrong up mountains, chasing down breakaway threats by other riders and making sure Armstrong was kept out of harm's way.

That was years ago.

Hamilton is finally coming clean about doping in the cycling world, and his version of the truth is anything but helpful to the planet's most famous cyclist. Once one of Armstrong's key teammates, Hamilton is casting more doubts on an unparalleled career that some people believe was tainted by drugs.

In an interview aired on ‘60 Minutes,’ Sunday, Hamilton said Armstrong not only took performance-enhancing drugs, he also encouraged other cyclists on the US Postal team to take them as part of an extensive doping program designed to keep Armstrong in front at the Tour de France.

"He obviously was the biggest rider in the team and he helped to call the shots," Hamilton said. "He doped himself, you know, like everybody else, but he was just being part of the culture of the sport."

In the interview, Hamilton revealed other observations about the US Postal team operation:

Team leaders, including doctors and managers, encouraged and supervised doping;

Doping was going on inside the U.S. Postal team even before Armstrong joined in 1998;

Performance-enhancing drugs, including EPO and human growth hormone, were handed out to cyclists in white lunch bags;

Team members were met at the airport, driven to hotels, told to lie down and give blood that could be transfused back into their bodies at a later date.

Hamilton said he held onto the secret for a long time, but decided it was time to tell the truth. This was his first public admission that he doped throughout his career. He said he has provided the same testimony to a Los Angeles-based grand jury looking into the Armstrong case.

"I feel bad that I had to go here and do this," Hamilton said. "But I think at end of the day, like I said, long-term, the sport's going to be better for it."

Armstrong long has denied doping and has never tested positive.

His attorney, Mark Fabiani, released a statement chiding the CBS report.

"We have already responded in great detail at http://www.facts4lance.com," Fabiani said.

"Throughout this entire process, CBS has demonstrated a serious lack of journalistic fairness and has elevated sensationalism over responsibility. CBS chose to rely on dubious sources while completely ignoring Lance's nearly 500 clean tests and the hundreds of former teammates and competitors who would have spoken about his work ethic and talent."

The ‘60 Minutes’ report also used unidentified sources to report that another Armstrong teammate and close friend, George Hincapie, testified to the grand jury that he and Armstrong supplied each other with EPO and discussed having used testosterone to prepare for races.

Armstrong posted a statement in support of Hincapie on the website: "We are confident that the statements attributed to Hincapie are inaccurate and that the reports of his testimony are unreliable."

Hincapie released a statement Friday, through his lawyer, saying he did not speak with ‘60 Minutes’ and didn't know where the show got its information.

He was not available to reporters Sunday at the Tour of California in Thousand Oaks, Calif.

Hamilton, meanwhile, described a systematic doping program run by Armstrong's U.S. Postal team. He said he offered the same testimony to the Los Angeles-based grand jury.

Federal prosecutors are investigating what essentially would have been a drug distribution network that was formed to keep Armstrong's teams running at the head of the pack.

The "60 Minutes" revelations, combined with recent requests from federal authorities for evidence in France, have fed a sense of growing trouble for the world's most famous cyclist, an international star and a cancer survivor who has raised millions of dollars to fight the disease.

In his interview, Hamilton said he saw Armstrong use the blood-boosting drug EPO during the 1999 Tour de France and in preparation for the 2000 and 2001 tours. He also described the transfusion protocol — from the pickup at the airport to the quick trip to the hotel to the time about halfway through the Tour when he and teammates had the blood put back into their bodies.

Armstrong won the world's most-revered race each year from 1999-2005.

But the case federal authorities are trying to compile won't be decided solely on whether Armstrong doped. It has more to do with a doping program allegedly run by the cyclist and his team — a program that could lead to fraud and conspiracy charges.

"He was the leader of the team and he expected for going in, for example the '99 Tour, (that) we were going to do everything possible to help Lance win," Hamilton said. "We had one objective, that's it."

Hamilton said it was a team effort, with Armstrong and the managers and trainers promoting the doping. One way he knew he was becoming important to the team was when he was handed one of the white lunch bags filled with doping supplies.

"In a way, it was also an honor that, 'Wow, like, they think I'm good enough to be with the A-team guys,'" he said.

The Associated Press reported last month that federal investigators asked French authorities to turn over evidence, including Armstrong's urine samples from 1999, the same year Hamilton said he saw Armstrong use the EPO during the Tour.

Armstrong's 1999 samples came under scrutiny in 2005 when the French sports daily L'Equipe reported that six of the samples had, in fact, tested positive for EPO when they were retested in 2004. An investigation by the International Cycling Union followed and concluded that the samples were mishandled and couldn't be used to prove anything.

But the samples still exist and are part of the cache of evidence authorities are seeking.

Those samples, along with bank and phone records and witness testimony about drug use, could be used to paint a picture of a doping program allegedly run by Armstrong and his U.S. Postal team.

Also in the "60 Minutes" report, Hamilton said Armstrong told him he had tested positive at the 2001 Tour de Suisse — a warm-up race for the Tour de France — but that he wasn't worried about it.

"He was so relaxed about it and he kind of just said it off the cuff and kind of laughed it off," Hamilton said. "It helped me sort of stay relaxed because, obviously, if he had a positive test, the ... team's going to lose the sponsorship, I'm going to lose my job. Not only am I going to lose my job but, you know, 50 to 60 other people are going to lose their jobs. ... There were a lot of consequences to a positive test."

Hamilton said Armstrong made a deal with the UCI, and they ‘figured out a way for it to go away.’

The Tour de Suisse allegations are similar to those made by Floyd Landis, who had his 2006 Tour de France title stripped for doping. After years of denying he cheated, Landis came out last year acknowledging he used PEDs and alleged Armstrong did, as well.

The ‘60 Minutes’ report referenced a letter provided by Armstrong's attorney that says UCI claims none of the positive samples belonged to Armstrong.

Armstrong's new website attacked Hamilton, who has been banned twice for doping despite his long insistence that he never cheated. Hamilton now admits he did use PEDs and has given his 2004 Olympic gold medal to the US Anti-Doping Agency.

"Tyler Hamilton is a confessed liar in search of a book deal — and he managed to dupe '60 Minutes,' the 'CBS Evening News,' and new anchor Scott Pelley," the website said. "Most people, though, will see this for exactly what it is: More washed-up cyclists talking trash for cash."