L'Equipe, the French sports newspaper, claimed today to have proof that Lance Armstrong used a performance-enhancing drug to win his first Tour de France in 1999.

The world's greatest cyclist and winner of seven Tour de France titles immediately denied the allegation in a statement on his website, saying "the witch hunt continues".

According to L'Equipe, six samples of Armstrong's urine, taken from various stages of the 1999 tour, have tested positive for the drug Erythropoietin (EPO), which could not be detected by anti-doping authorities until 2001. L'Equipe says that the tests were carried out in 2004.

Use of EPO is thought to have been rife among cyclists until reliable methods of detection were available. Injections of the hormone, which are given to victims of kidney failure, can increase a rider's endurance by up to 30 per cent by driving up the production of oxygen-rich red blood cells.

In 1998, Hundreds of doses of EPO and needles were found in a car belonging to the Festina cycling team.

Devoting four pages to the story, that appears under a headline "The Armstrong Lie", L'Equipe claims that the Armstrong urine samples were tested by the French national anti-doping laboratory at Châtenay-Malabry, where scientists were practising their techniques to detect EPO.

"There is no possible doubt about the validity of the result, even though the analysis was carried out five years after the sample was taken," the newspaper quotes Professor Jacques de Ceaurriz, the director of Châtenay-Malabry, as saying.

Although L'Equipe says "the facts are indisputable", the newspaper acknowledges that the method of testing used on Armstrong's samples means that the case will not be brought before the Union Cycliste International (UCI), which governs the sport.

Armstrong, who has been accused of taking performance-enhancing drugs by the French press on several occasions, denied today's story before it was even published. A statement appeared on his website last night.

"Yet again, a European newspaper has reported that I have tested positive for performance enhancing drugs. Tomorrow’s L’Equipe, a French sports daily, is reporting that my 1999 samples were positive. Unfortunately, the witch hunt continues and tomorrow’s article is nothing short of tabloid journalism.

"The paper even admits in its own article that the science in question here is faulty and that I have no way to defend myself," said the statement.

"I will simply restate what I have said many times: I have never taken performance-enhancing drugs."

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