Tour de Farce - German TV stops Coverage

Vinokourov won two stages within three days this week

Kazakh rider Alexandre Vinokourov tested positive for blood doping after winning Saturday's time-trial stage.

And Prudhomme said: "This has to change now. The re-conquering of cycling has to be done with the Tour de France.

"I started this job believing that we could change this system but it's not enough: there has to be a revolution."

606: DEBATE It's a disgrace but it's a good thing that they are being caught - it's the only way to clean up the sport k1gannon

The 33-year-old, who won Saturday's time trial in Albi, reportedly had two different kinds of red blood cells, indicating he has taken blood from someone of a compatible group.

Even before Tuesday's bombshell, Tour leader Michael Rasmussen was battling suspicions for missing pre-tour doping tests, although he still seems likely to claim victory in Paris on Sunday.

BLOOD DOPING EXPLAINED What is it? Administration of red blood cells to increase the blood's oxygen-carrying capacity How is it done? Injection with someone else's red blood cells; removing own blood, storing it and returning it once body has replaced it Why do it? The better the blood's oxygen-carrying capacity, the greater one's endurance Side effects: Blood clots, overload of circulatory system, kidney damage, transmission of infectious diseases such as HIV Chances of being caught: Test can only detect it if the blood comes from a donor

In addition, 2006 Giro winner Ivan Basso was recently handed a two-year ban and 1996 Tour de France winner Bjarne Riis admitted using performance-enhancing drugs, as did former Telekom team-mates Eric Zabel, Udo Boelts, Bert Dietz, Christian Henn and Rolf Aldag.

Prudhomme expressed his disappointment over the latest setback and urged riders to remain clean for the good of the sport.

"The start in London was a formidable occasion to re-conquer," he said. "But there has been an absolute failure of the system.

"The riders have to understand that they are playing a game of Russian roulette if they are doping.

Everyone has been suspicious of the Astana team Bradley Wiggins

"Doping ruins our childhood dreams. Vinokourov has cheated and the only possible answer was - leave."

Britain's Olympic track champion Bradley Wiggins revealed he had suspicions over Vinokourov's performance in Saturday's time trial.

"I know that to put two minutes into me what power Vino would need and the effort he would have had to make and it didn't add up," he told the Guardian.

Prudhomme is demanding action after the latest drugs scandal

"But when you saw him limping the week before you couldn't help thinking about it. I think everyone has been suspicious of the Astana team.

"It is a disaster for the sport. There will be no cycling in 10 years if this goes on."

Fellow Briton David Millar, who has been an outspoken campaigner against doping since serving a two-year ban for using erythropoietin, believes cycling would take "five to years" to get out its drugs problem.

He said: "The bottom line is it is, it is finally good because the controls work, but I'm gutted as Vinokourov was one of my favourite riders."

Vinokourov was hotly tipped for this year's title but lost time in a bad crash on stage five and slipped further back in the stages in the Alps.