American Floyd Landis is likely to lose his Tour de France title after a second drugs sample confirmed a positive test for excessive amounts of the male sex hormone testosterone.
A statement issued by the International Cycling Union (UCI) on Saturday said Landis's B sample taken after his win in the 17th stage on July 20 had confirmed a doping offence.
Landis, who again denied ever taking drugs, was immediately sacked by his Swiss team Phonak.
He will now probably become the first rider ever to be stripped of the Tour de France title for doping, lose 450,000 euros ($575,700) prize money and face a two-year ban from the sport.
"Landis will be dismissed without notice for violating the team's internal Code of Ethics," Phonak said in a statement.
"Landis will continue to have legal options to contest the findings. However, this will be his personal affair and the Phonak team will no longer be involved in that."
In a statement on his Web site the 30-year-old American said he had never taken a banned substance.
"I have never taken any banned substance, including testosterone. I was the strongest man in the Tour de France, and that is why I am the champion," Landis said.
"I will fight these charges with the same determination and intensity that I bring to my training and racing. It is now my goal to clear my name and restore what I worked so hard to achieve."
EXPERTS
His lawyer Howard Jacobs said he was waiting to receive full laboratory documentation for the B test.
"In consultation with some of the leading medical and scientific experts, we will prove that Floyd Landis's victory in the 2006 Tour de France was not aided in any respect by the use of any banned substances," Jacobs said.
Landis and Jacobs will also question the UCI's premature release of the A sample findings and the anonymous leak of the carbon-isotope test results to the New York Times on July 31, the statement said.
The UCI statement said an analysis of the B sample confirmed the result of an adverse analytical finding notified by the anti-doping laboratory of Paris on July 26.
"In accordance to the anti-doping rules, the Anti-Doping Commission of the UCI will request that the USA Cycling Federation open a disciplinary procedure against the rider."
Spaniard Oscar Pereiro Sio, who finished second 57 seconds adrift of Landis in the overall standings, is now likely to be declared the winner of the race.
ASTOUNDING COMEBACK
Pereiro, who is due to give a news conference in Vigo at 1600 GMT (5 p.m. British Time), would then become the first Spaniard to win the Tour since Miguel Indurain's last victory in 1995.
Landis, 30, tested positive for testosterone after an astounding comeback in the last mountain stage of the world's greatest cycling race. It came just a day after a very poor performance which all but knocked him out of contention.
Landis now has 10 days to respond to the documents that are provided, according to U.S Anti-Doping Agency (USADA) rules.
Those documents, Landis's response and any documents USADA would provide will go to a review panel some time after the 10 days.
The review panel will make a recommendation whether or not there is a case. USADA, based on that recommendation, will then decide whether to charge Landis.
If USADA does charge the Phonak rider, he would have an opportunity to contest that decision and the recommended sanction before a U.S panel of judges.
Landis's lawyers could then take the matter to the Court of Arbitration for Sport (CAS) and a long procedure would begin.
Testosterone speeds up recovery after exercise and generally improves stamina and strength. Last weekend Olympic 100 metres champion Justin Gatlin admitted he had tested positive for the same hormone.