(USA TODAY) - Lance Armstrong faces new doping charges brought against him by the U.S. Anti-Doping Agency.

Armstrong, who retired from competitive cycling in 2011, confirmed on Twitter on Wednesday that he was informed of the charges in a letter sent by USADA.

His seven Tour de France titles could also be in jeopardy, the Washington Post first reported in a story published Wednesday on its website. The newspaper obtained a copy of a letter sent to Armstrong on Tuesday that says blood samples collected in 2009 and 2010 were "fully consistent with blood manipulation including EPO use and/or blood transfusions."

The cyclist has strongly denied doping accusations throughout his career. He has never tested positive.

He is now banned from competing in triathlons as a result of the USADA charges, The Post reported. The letter alleges that Armstrong and five others associated with his cycling team were involved in a doping program that included the use of blood transfusions and performance enhancing drugs, the report said.

Armstrong said in his statement that USADA "intends to again dredge up discredited allegations dating back more than 16 years."

The statement continued: "I have never doped, and, unlike many of my accusers, I have competed as an endurance athlete for 25 years with no spike in performance, passed more than 500 drug tests and never failed one."

The U.S. Anti-Doping Agency is the body in charge of drug testing for Olympic sports. It does not have the power to file criminal charges.

In February, federal prosecutors dropped a two-year investigation of Armstrong, looking at whether he and his teammates participated in a doping program while he was riding for the U.S. Postal Service team. He won the Tour de France from 1999 to 2005.

In the federal investigation, a grand jury in Los Angeles heard evidence from Armstrong's former teammates and associates. When prosecutors announced they were closing the case, they did not disclose a reason for the decision.

From USA Today staff reports

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