LANNEMEZAN, France - Just when the race was getting interesting at the Tour de France, another doping scandal erupted.

The 11th-stage victory Wednesday by Norwegian veteran Kurt-Asle Arvesen took a back seat to the arrest of Spain’s Moises Duenas Nevado after he tested positive for the banned performance enhancer EPO in the second doping bust this Tour.

“I just can’t understand when are these guys are going to learn,” International Cycling Union president Pat McQuaid said by phone. “If the ’B’ sample is positive, then all I can say is the guy’s a fool. The net is closing in.”

McQuaid said the lure of glory in cycling’s main event influences doping.

“The Tour is the biggest event in the world and people will take that risk,” McQuaid said. “It’s unfortunate. Throughout the rest of the year we don’t get that many positives in other races.”

“I’m very, very sorry for the image of cycling,” said Cadel Evans of Australia, lamenting the case that overshadowed his first ride in the yellow jersey on the 104.1-mile stage from Lannemezan to Foix. He said he had an opinion on the “sensitive issue” — but was keeping it to himself.

Before the stage began, police swept into the hotel in Tarbes where Duenas Nevado’s Barloworld team was staying. They detained him and seized unspecified “banned medicines” from his room, team officials said.

The 27-year-old Spaniard, riding in his third Tour de France, tested positive for EPO after the fourth stage time trial in Cholet on July 8, said Pierre Bordry, head of the French anti-doping agency.

Duenas Nevado, who had been 19th overall, was immediately suspended by his team and ousted from the race. On orders from a state prosecutor, police were holding him overnight for questioning — notably about where he may have obtained EPO, a police official said. Under French law, he can be held up to 24 hours.

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The drug bust was only the latest in a string of doping scandals that have rocked cycling in recent years — and especially the Tour, its main event. Since the start of last year’s race, at least a half-dozen doping-related cases have hit the Tour.

“I’m shocked,” Barloworld manager Claudio Corti said in a statement. “The team is not involved in this story at all, and we’ll take severe action against anyone who damages our credibility and the image of our team.”

The case was the second positive EPO test in this Tour. Spanish veteran Manuel Beltran — a former teammate of seven-time winner Lance Armstrong — was sent home for testing positive after the first stage this year.

Duenos Nevado recorded his best Tour finish of 39th last year. His previous achievements included victories in the Regio Tour last year, and the Tour de l’Avenir in 2006.

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The two Spaniards are lesser-known riders. Above all, their positive tests fan questions about how other riders can possibly fare better without turning to performance enhancers or other types of cheating.

Barloworld got even more bad news Wednesday: Two team riders pulled out of the race after sustaining injuries from a crash about midway through the stage. Colombia’s Felix Cardenas suffered a deep cut in his left knee and Paolo Longo Borghini of Italy broke his right collarbone, the race doctor said.

Barloworld is down to the minimum five riders. The team’s leader, Colombian rider Juan Mauricio Soler, pulled out of the race last week after injuring his wrists in a crash during the first stage. Soler was the King of the Mountains champion as the Tour’s best climber last year.

The drug bust siphoned off attention from what looks to be a still-wide open race, whose outcome is likely to be determined in three rides in the Alps starting Sunday and a time trial a day before the July 27 finish in Paris.