COL D'AUBISQUE, France - The Tour de France lurched into a fresh crisis on Wednesday when race leader Michael Rasmussen was sacked by his Rabobank team and a second rider in 24 hours was announced to have failed a doping test.

Rabobank team rider Michael Rasmussen of Denmark cycles to win the 16th stage of the 94th Tour de France cycling race between Orthez and Gourette-Col d'Aubisque in this July 25, 2007 file photo.[Reuters]

The Dane had pulled further clear of his main rivals with a gutsy stage victory earlier in the day but his team said he would not start Thursday's 17th stage after lying to them over his training whereabouts last month.

Rabobank director Theo de Rooy was quoted on Dutch TV as saying: "Several times he said where he was training and it proved to be wrong. The management of the team received that information several times and today we received new information."

The team said the Dane had told them he was in Mexico when he had in fact been in Italy.

Rabobank said in statement late on Wednesday: "Rabobank is shocked and enormously disappointed that Rasmussen has lied about his whereabouts."

Rasmussen's dismissal is possibly the biggest hammer-blow to the Tour's credibility following hard on the heels of positive dope tests on pre-race favourite Alexander Vinokourov on Tuesday and Italy's Cristian Moreni on Wednesday.

Rasmussen, 33, had already received two warnings from the UCI for failing to provide the sport's governing body with his personal schedule.

UCI president Pat McQuaid told Reuters by phone: "I wonder why they did not make the decision when they had all the information in June. However, it is a zero tolerance policy and I can only applaud it."

Tour de France director Christian Prudhomme told Reuters: "The important thing is not that he has been sacked by his team but that he will not be at the start of the stage tomorrow."

Cofidis rider Moreni's positive test was announced less than a day after the Tour was rocked by the news of Vinokourov's blood-doping violation.

The 34-year-old, Italian champion in 2004, failed a dope test for the male sex hormone testosterone after last Thursday's 11th stage from Marseille to Montpellier.

Both men's teams have now quit the Tour which ends in Paris on Sunday.

Race jury president Didier Simon told reporters on Wednesday Moreni had had three hours to request an analysis of the B sample but had not asked for it.

Cofidis later announced they were withdrawing from the Tour, joining Vinokourov's Astana on the sidelines.

"It's the only thing to do in such circumstances," Cofidis president Francois Migraine said.

Patrice Clerc, president of organisers ASO, agreed: "It's a responsible decision. It is sad because I know this team has made a lot of efforts to fight for a clean sport."

Ironically, only on Tuesday Cofidis set up the Movement for Credible Cycling with other teams competing in the Tour, asking for all to abide by their charter adopted in 2005 under which riders implicated in doping affairs are not allowed to race.

Cofidis team manager Eric Boyer said of Wednesday's news: "It's an earthquake. This can have very serious consequences for the future of the team."

Witnesses said Moreni was arrested by French police after Wednesday's stage and the Cofidis team hotel in Lescar searched.

Moreni finished 41st on Wednesday, well behind stage winner Rasmussen, who had appeared on course for overall victory after the Dane opened up a lead of three minutes and 10 seconds over nearest rival Alberto Contador of Spain.

Jeered at the start of the stage, Rasmussen told reporters after his victory: "I have been booed but there is such a frustration from the fans and the peloton after Vino's (Vinokourov's) positive test and that frustration came down on me."

"Now I understand what (Lance) Armstrong endured during seven years," Rasmussen said in reference to the seven-times Tour champion, who faced several allegations of doping, all of which he strongly denied.

"I want to add that Vino's positive test shows the anti-doping system works. I have been tested 14 times and never been positive."

The UCI said in a statement on Wednesday: "Whereas the question of the culpability of Mr Vinokourov will be answered by the competent disciplinary bodies, the UCI realises that the mere fact of an adverse analytical finding is detrimental to the image of cycling and of the race where the finding occurred, in this case the Tour de France.

"More than the financial cost, this is the painful price for UCI's intensive anti-doping fight. Race organiser ASO has to be congratulated for its financial and moral support in the fight against doping."