American cyclist Lance Armstrong says "The witch hunt continues," as he responded to allegations of doping.

The French newspaper L'Equipe reported on Tuesday that six of Armstrong's urine samples collected from the 1999 Tour showed "indisputable" traces of EPO, or erythropoietin. L'Equipe, a company with close ties to management of the Tour de France, titled the article "The Armstrong Lie."

At the time the samples were taken, there were no tests to detect EPO, which increases the level of red blood cells. However the samples were preserved and have been retested by a lab near Paris.

The laboratory, which developed the test, said that they cannot confirm that the results were Armstrong's. There are many questions surrounding the validity of the tests, which took place on "B" samples only, as all the "A" samples had been depleted.

Armstrong, who recently won the Tour for the seventh straight time, has repeatedly denied ever taking performance-enhancing drugs

"If it's true, I would of course be disappointed," said Germany's Jan Ullrich, 1997 Tour winner. "Lance is the greatest of our time and maybe somebody's trying to put him down. I don't know what it's about, so all of this is very speculative."

Tour director Jean-Marie Leblanc said that L'Equipe's report seemed "very complete, very professional, very meticulous" and that it "appears credible."