The U.S. Anti-Doping Agency has made formal allegations of doping violations against Lance Armstrong that could strip him of all seven of his Tour de France titles.

Armstrong received a letter Tuesday that said USADA alleges he possessed and used testosterone and blood-doping products while a member of the U.S. Postal racing team, beginning in 1998.

The Washington Post first reported the letter of notice Wednesday afternoon.

Under USADA procedures, Armstrong has 10 days to respond to the charges, after which an independent anti-doping review panel would look at the USADA evidence and decide whether formally to charge Armstrong with doping.

If he contests the charges, he is entitled to a "trial," where evidence would be presented and witnesses would testify under oath. It would be up to Armstrong whether the hearing is open to the public.

Armstrong denied the allegations Wednesday.

"These are the very same charges and the same witnesses that the Justice Department chose not to pursue after a two-year investigation," he said in a statement released on his website. "These charges are baseless, motivated by spite and advanced through testimony bought and paid for by promises of anonymity and immunity. ... USADA's malice, its methods, its star-chamber practices, and its decision to punish first and adjudicate later all are at odds with our ideals of fairness and fair play.

"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. That USADA ignores this fundamental distinction and charges me instead of the admitted dopers says far more about USADA, its lack of fairness and this vendetta than it does about my guilt or innocence. Any fair consideration of these allegations has and will continue to vindicate me."