The U.S. Anti-Doping Agency on Friday stripped famed cyclist Lance Armstrong of his seven Tour de France titles.

It also negated any other results he may have earned from Aug. 1, 1998, through the present and banned him for life from sanctioned cycling events for using and distributing performance-enhancing drugs and then covering it up.

Armstrong, who retired from competitive cycling last year after winning the Tour de France from 1999 through 2005, has denied doping and said the USADA is on a "witch hunt." He said the agency does not have physical evidence against him, and he did not cooperate with the investigation.

"Unfortunately, Lance is not someone we should look up to," said David Chauner, a member of the U.S. Cycling Hall of Fame, a two-time U.S. Olympian, and the designer and organizer of the annual pro cycling race in Philadelphia. "He was a great cyclist, and he's done a lot for humanity. But the fact that he was engaged in a [doping] program like this - and actually leading the charge - is reprehensible."

The USADA said it expected cycling's governing body to take similar action, but the International Cycling Union (UCI) delayed a response, saying it first wanted a full explanation of the USADA decision.

The Amaury Sport Organization, which runs the Tour de France, and the International Olympic Committee said they would not react until hearing more from both the UCI and USADA. Armstrong won a bronze medal in the individual road time trial at the 2000 Sydney Olympics.

Travis T. Tygart, the USADA chief executive officer, said in a statement Friday that he had no choice but to prosecute Armstrong.

"Any time we have overwhelming proof of doping, our mandate is to initiate the case through the process and see it to conclusion, as was done in this case," Tygart said.

Armstrong, already a world-class cyclist, became famous world-wide after he was found to have stage-three testicular cancer in 1996. The tumors then spread to his abdomen, lungs, lymph nodes, and brain before surgery and chemotherapy left him cancer-free in 1997. He went on to create a foundation, Livestrong, that he says has raised more than $470 million to fight cancer.

Several of his foundation's sponsors have said they will continue to support its efforts despite the controversy.

"If I thought for one moment that by participating in USADA's process I could confront these allegations in a fair setting and - once and for all - put these charges to rest, I would jump at the chance," Armstrong said in a statement Thursday.

Armstrong, 40, is accused of using EPO, blood transfusions, testosterone, corticosteroids, and masking agents to improve his performances. He is also accused of encouraging others on his former team, U.S. Postal Service, to use the drugs and cover it up.

The USADA said in a statement that Armstrong could have contested its charges in an independent arbitration process but chose not to by the deadline Thursday night. Armstrong had challenged the USADA arbitration process in federal court, but the lawsuit was dismissed Monday in Austin, Texas.

So the USADA said it "was required under the applicable rules, including the World Anti-Doping Code under which [Armstrong] is accountable, to disqualify his competitive results and suspend him from all future competition."

The USADA said that all the evidence it had collected against Armstrong would have been presented in an open proceeding for him to challenge had he gone to arbitration.

Former rival Filippo Simeoni of Italy said he was "perplexed, because someone like [Armstrong], with all the fame and popularity and millions of dollars he has, should fight to the end if he's innocent."

According to the USADA, the evidence against Armstrong arose from "disclosures made to USADA [in June] by more than a dozen witnesses who agreed to testify and provide evidence about their firsthand experience and/or knowledge of the doping activity of those involved in the conspiracy as well as analytical data."

Floyd Landis, a native of Lancaster County and Armstrong's former teammate who was stripped of the 2006 Tour de France title because of doping, sent cycling authorities e-mails in 2010 accusing Armstrong and U.S. Postal team officials of breaking doping rules.

On Friday in San Diego, Landis, in court answering charges of wire fraud for lying to financial donors about his own drug use, said, "I really don't know what the solution is for the sport of cycling. That's not my issue anymore."

Armstrong's longtime coach, Johan Bruyneel, came to his defense Friday and said he was the victim of an "unjust" legal case by the USADA.

"I'm disappointed for Lance and for cycling in general that things have reached a stage where Lance feels that he has had enough and is no longer willing to participate in USADA's campaign against him," Bruyneel wrote on his personal website.

Chauner said he remembered the 21-year-old Armstrong as a charismatic competitor with a great personality. Six years before he won his first Tour de France title, Armstrong endured the Manayunk Wall to capture Chauner's 1993 U.S. Pro Cycling Championship.

"He basically had all the talent in the world," Chauner said.

He said Philadelphia's annual cycling race will no longer use Armstrong's previous victory to promote the race. Of the last 14 Tour de France winners, nine have lost their titles because of doping, which has affected the way Chauner organizes his race.

"We've stayed away from trying to attract the top professionals in the last few years just because we don't want to be associated with what's been happening over in Europe," Chauner said.