Landis, 30, tested positive for the male sex hormone after winning stage 17 of the race in the French Alps.

He will ask for a second urine sample to be tested but his lawyer Luis Sanz said they expected the B test to be positive -- a result which would strip him of his Tour title and earn a probable two-year ban.

It would be the first time a Tour champion has been disqualified for doping.

Cycling has been blighted by doping but Tour organisers said Landis's test and the pre-race case showed they were cracking down more heavily on transgressors.

The sport has become hugely popular in Germany since Ullrich's Tour victory, but the doping scandals have prompted major networks ARD and ZDF, who cover the Tour de France extensively, to consider whether they will drop it in the future.