French authorities have launched a preliminary investigation into doping allegations levied against six-time Tour de France champion Lance Armstrong.
At the centre of the probe is Emma O'Reilly, Armstrong's former assistant.
In the French-language book, L.A. Confidential, the Secrets of Lance Armstrong, O'Reilly claims the American cyclist had her dispose of used syringes. O'Reilly also said Armstrong borrowed makeup to cover up needle marks on his arms.
Armstrong has been dogged by suggestions that he's used performance-enhancing substances since 1999, when he made a miraculous recovery from testicular cancer to win his first Tour de France.
Armstrong has also been connected with notorious Italian sports doctor Michele Ferrari, whose name has been linked to the endurance-boosting drug EPO.
Armstrong has scoffed at the book's claims as "absolutely untrue" and denies ever taking performance-enhancing drugs. Armstrong has only tested positive once in his career â for a cortisone-based cream in 1999.
"Let me make one thing emphatically clear: I believe in clean and fair competition," Armstrong said in a statement issued on Friday. "As I have said before, I do not use and have never used performance-enhancing drugs."
Last July, a Paris appeals court turned down Armstrong's request that the book, written by journalists David Walsh and Pierre Ballester, should include his denial of the allegations.
"They are also welcome to review my long history of tests for performance-enhancing drugs, which I have never failed," Armstrong added. "I will be competing in Paris-Nice in March. I am confident my name will be cleared, and I look forward to racing in France for years to come."