The Tour de France sustained a new blow Wednesday after a senior French doping official said yet another rider failed a doping test -- this time for testosterone.
The revelation came a day after Alexandre Vinokourov and his Astana team were disqualified because he tested positive for a banned blood transfusion.
The doping official said he did not know the identity of the cyclist who tested positive for testosterone. The official spoke on condition of anonymity because he was not authorized to discuss the case with reporters.
Also Wednesday, dozens of Tour de France riders demonstrated their anger over repeated doping scandals by staging a silent protest at the start of the 16th stage, a 135.8-mile ride from Orthez to Gourette-Col d'Aubisque.
The pack of riders split into two groups: those who took the start as normal -- including controversial race leader Michael Rasmussen -- and those who protested by hanging back, causing a 13-minute delay.
Meanwhile, Spanish officials announced that at least one small explosive device detonated along the day's route as the race nosed into northern Spain. Spanish media said the blast or blasts were preceded by a call in the name of Basque separatist group ETA, but Spain's Interior Ministry said it could not confirm. No injuries were reported.
French sports newspaper L'Equipe, which broke the story on Vinoukourov, said on its Web site Wednesday the latest case resulted from a test conducted on stage 11 of the Tour last Thursday.
L'Equipe did not name the rider. It said the UCI, cycling's governing body, would announce the latest test result shortly. The UCI's top anti-doping official, Anne Gripper, declined comment to the Associated Press.
Urine tests are conducted daily at the Tour on the stage winner, the race leader and other selected riders.
Stage 11, from Marseille to Montpellier in southeast France, was won by sprinter Robert Hunter, a South African on the Barloworld team. The race leader then -- and now -- is Rasmussen, who is riding under a cloud of suspicion because he skipped doping tests before the three-week Tour began.
The Dane started Wednesday with a 2:23 lead over Discovery team rider Alberto Contador of Spain.
The identity of the other riders tested that day was not immediately known. L'Equipe said the test analysis was conducted by the Chatenay-Malabry lab on the outskirts of Paris. Traces of testosterone were found in the urine sample, the newspaper reported. The test showed that the testosterone was administered and that the hormone was not naturally occurring.
The protest riders let Rasmussen, star sprinter Tom Boonen and others not involved ride away -- but caught up with them further down the road. Many of the riders involved in the symbolic protest were from French teams that have long complained that doping is ruining the sport. Fans booed Rasmussen at the start. The Dane is under a cloud of suspicion because he skipped doping tests before the Tour began.
The Tour's Web site said German squad Gerolsteiner also took part in the protest. Some of the French teams involved included Credit Agricole, Cofidis, FDJeux, Bouygues Telecom and Agritubel.
Tour organizers announced that 14 riders were subjected to blood tests early Wednesday. They were from French teams Cofidis and AG2R. The tests were all negative. In all, 225 blood tests have been conducted so far at the three-week race. Of those, just one -- for Vinokourov -- was positive.
Without the Kazakh rider and Astana, the field was reduced to 151 riders on Wednesday. The team's withdrawal also meant two of the top 10 riders were out -- Andreas Kloeden of Germany, who had been fifth, and Kazakh Andrey Kashechkin, who had been eighth. Wednesday's stage featured four huge climbs, culminating with an uphill finish so tough it does not even have a rating.
Rasmussen was aiming to get through the stage without losing time to his main rivals, so he can embark on the last major hurdle -- a time trial on Saturday -- in a commanding position. Vinokourov tested positive for a blood transfusion after he won last Saturday's time trial. On Monday, Vinokourov also won stage 15 -- a tough climb in the Pyrenees. Those performances marked a remarkable recovery from a crash that had ruined the first week of his race.
Vinokourov told the French sports daily L'Equipe for Wednesday's edition that he had not cheated.
"It's a mistake. I never doped, that's not the way I see my profession," the newspaper quoted him as saying. "I think it's a mistake in part due to my crash. I have spoken to the team doctors who had a hypothesis that there was an enormous amount of blood in my thighs, which could have led to my positive test."
Vinokourov claimed to be the victim of a "provocation." "It's been going on for months and today they're managing to demolish me," he said. "The setting up of our team made a lot of people jealous and now we're paying the price. It's a shame to leave the Tour this way, but I don't want to waste time in proving my innocence."
------ Associated Press Writers John Leicester in Paris and Jean-Luc Courthial in Gourette contributed to this report.