The cycling world has been rocked after it emerged that Tour de France winner Floyd Landis failed a drugs test during the race.

The American's positive test after stage 17 from Saint-Jean-de-Maurienne to Morzine - which he won by almost six minutes to charge back into contention - revealed an abnormally high level of testosterone.

A spokesperson for his team, Phonak, confirmed to PA Sport: 'He (Landis) has tested positive for testosterone.'

And a statement on the team's website revealed: 'The Phonak Cycling Team was notified yesterday by the UCI (International Cycling Union) about an unusual level of Testosterone/Epitestosterone ratio in the test made on Floyd Landis after stage 17 of the Tour de France.

'The team management and the rider were both totally surprised by this physiological result. The rider will ask in the upcoming days for the counter analysis to prove either that this result is coming from a natural process or that this is resulting from a mistake in the confirmation.

'In application of the Pro Tour Ethical Code, the rider will not race anymore until this problem is totally clear. If the result of the B sample analysis confirms the result of the A sample, the rider will be dismissed and will then pass the corresponding endocrinological examinations.'

Landis could be stripped of his title if found guilty and when asked if that would be the case, UCI Spokesman Enrico Carpani told PA Sport: 'We have only just released this (statement) two or three minutes ago.

'We have to await the final decision of the authorities. 'I believe yes, but I am not a lawyer. Please do not be too quick in drawing your conclusions.'

Should Landis have his title taken away from him, Spaniard Oscar Pereiro would be the likely beneficiary.

The Caisse D'Epargne rider finished second in the event, 57 seconds behind Landis, and would be next in line if the title were reassigned.

If Landis' B-test also returns a positive result, it will have serious ramifications for the sport, which has long been dogged by speculation regarding doping.

A number of racers, including pre-race favourites Jan Ullrich of T-Mobile and Ivan Basso of Team CSC, were withdrawn on the eve of the Tour after Spanish investigation Operacion Puerto linked their names to a Madrid-based doping ring.