The Tour de France was hit by doping again on Wednesday when Moises Duenas Nevado of the Barloworld team became the second Spaniard to test positive for the blood-boosting erythropoietin (EPO).
The French-Anti Doping Agency (AFLD) said that Duenas Nevado, who joined Barloworld two years ago, had failed a dope test after last week's fourth stage, a time trial in Cholet.
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The 27-year-old was immediately withdrawn from the race by his team and was detained by police in Tarbes, in Southwestern France. Police said he would be detained until Thursday morning.
Barloworld were allowed to continue in the event because of a pre-race contract with organisers saying teams can carry on if an offending rider is removed.
"We notified Moises Duenas Nevado that he had tested positive for EPO after the fourth stage this morning at 0900 a.m. (0700 GMT)," AFLD president Pierre Bordry said.
Police raided the hotel where Barloworld were staying before the start of the stage and found banned substances in the rider's room.
"It has emerged that some banned medicines that were absolutely not supplied or prescribed by the team doctor were found in Moises Duenas's room", Barloworld said on their Web site.
Team manager Claudio Corti said: "He seems to have secretly used banned substances, hiding everything from everybody else in the team."
Patrice Lamielle, a colonel in the French gendarmerie, said: "He has been taken into custody and will be presented before the investigating judge tonight.
"We found some substances in his room but I can't tell you what it is until they have been analysed. The investigation is on Moises Duenas Nevado only."
Duenas Nevado, who had been 19th in the overall standings, faces exclusion from his team and a two-year suspension.
Rocked in recent years by a number of doping scandals, this year's race had been free of controversy until last Friday when Liquigas rider Manuel Beltran was arrested by French police after it was announced he had tested positive for EPO.
Pat McQuaid, the president of the International Cycling Union (UCI), said Spain seemed to fail to get the message in the fight against doping.
"My first reaction is a reaction of great anger," McQuaid said, responding to Wednesday's news. "He is an idiot."
McQuaid added: "It is interesting to see that it is the second Spanish rider [to fail a dope test on the Tour]. Spain are slower to get the message."
His remarks drew a swift response from Spanish sports minister Jaime Lissavetzky who told Spanish state radio: "I respect everyone's opinion but McQuaid seems to be picking fights with everyone these days.
"He knows very well we are making great efforts on this theme and what he has said is very unfortunate."
Duenas Nevado was taken by police for questioning before the start of 11th stage which was won by Norway's Kurt-Asle Arvesen of the CSC team.
Australian Cadel Evans retained the overall leader's yellow jersey after finishing safely in the bunch, but there was more bad news on the road for Barloworld.
On top of Duenas Nevado's exclusion, two other riders from the team exited the race after falling -- Italian Longo Borghini and Spain's Felix Cardenas.
In another incident, an AG2r-La Mondiale team car struck two adults and two children in the crowd behind a barrier near the finish line after the driver seemed to lose control.
The four were taken to hospital with bruises and suspected fractures. Police said their condition is not serious.