LAVELANET, France (AP) -- The Tour de France was thrown into chaos again Thursday after Italian rider Riccardo Ricco became the third rider to test positive for the performance enhancer EPO.

Ricco's Saunier-Duval team withdrew from the Tour and suspended all of its activities after news of the rider's test for the banned blood booster. For the third year in a row, the showcase race has been marred by doping.

Last year, Alexandre Vinokourov tested positive for a blood transfusion, Cristian Moreni was caught using testosterone and Iban Mayo - also with Saunier-Duval - tested positive for EPO before being cleared by the Spanish cycling federation.

Two years ago, American rider Floyd Landis was stripped of his title after using synthetic testosterone.

"I'm glad they got caught. The Tour needs to continue and get to the finish in Paris," International Cycling Union president Pat McQuaid told The Associated Press. "It's another blow to the sport but I have to see it in light of the fact that they're getting caught and going to be thrown out."

Ricco, a 24-year-old Italian who won two Tour stages this year, tested positive after the fourth stage, a time trial in the western town of Cholet.

Pierre Bordry, the head of the French anti-doping agency, announced the result, leading to the team's withdrawal shortly before the start of the 12th stage - a 104.7-mile run from Lavelanet to Narbonne.

"It's a team decision not to start the race," Saunier-Duval sporting director Matxin Fernandez said. "He's our leader, we can't act as if nothing happened."

Saunier-Duval is the first team to drop out of this year's Tour. Last year, two teams withdrew and race leader Michael Rasmussen was kicked out just days before the end for lying about his whereabouts to avoid pre-Tour testing.

Cofidis dropped out after Moreni's positive test, Vinokourov's Kazakh-owned Astana team was kicked out by race organizer ASO after he tested positive.

In an attempt to salvage cycling's showcase event, race organizers had pledged a tougher approach to combatting drug cheats at this year's Tour. Eight specially trained chaperones shadow riders after each stage, even climbing onto team buses, to ensure cyclists go to post-stage anti-doping checks.

As part of the clampdown, the French anti-doping agency tested riders before the race and found that some 20 had abnormal levels of hematocrit without exceeding the limit. High levels of hematocrit are indicators of EPO use but do not confirm it.

Ricco was taken off the Saunier-Duval team bus by police ahead of the stage and booed by spectators.

Ricco was the runner-up in the Giro d'Italia and is the biggest name among the three cyclists involved in doping cases at this year's Tour. He won the sixth and ninth stages and was ninth overall before the start of Thursday's stage - 2 minutes, 29 seconds behind race leader Cadel Evans of Australia.

Spanish veteran Manuel Beltran - a former teammate of seven-time Tour champion Lance Armstrong - was sent home for testing positive for EPO after the first stage this year. Another Spaniard, Moises Duenas Nevado, was detained by police and expelled from the race on Wednesday after testing positive for EPO - like Ricco, after the fourth stage.

Ricco had come under suspicion about what he says is his naturally high hematocrit level - the volume of red blood cells.

Following his victory in the ninth stage, Ricco said he has had high hematocrit levels "ever since I was little," adding "I hope soon that everybody will stop speaking about that."

Reached by telephone, the Italian cycling federation said it was waiting for details of Ricco's test before commenting.

Ricco's popularity in Italy rocketed with his two Tour stage wins, even gaining front-page coverage in the football-focused Gazzetta dello Sport.

The rider has said his idol was Marco Pantani - the last Italian to win the Tour, in 1998. Pantani faced doping allegations throughout his career. He died of a cocaine overdose on Valentine's Day in 2004.

The news on Ricco came as judicial officials continued to question Duenas Nevado. He was detained by police Wednesday in the southwestern town of Tarbes, at a hotel where his Barloworld team was staying. Police also searched his hotel room.

Gerard Aldige, the state prosecutor in Tarbes, told The Associated Press that police found "numerous small medical materials like syringes, needles, and medical drip bags which theoretically a cyclist should not have in his room."

Aldige said Duenas Nevado faced preliminary criminal charges for "holding and using poisonous substances or plants" and "prohibited importing of merchandise."

Other substances were also found, including capsules and gels, but that tests will be required to determine their composition, Aldige said. He said one medicine not authorized for sale in France was also found - though he did not elaborate.

Beltran, who rides for Liquigas, was kicked out of the Tour on July 11 after he tested positive for EPO.

In addition to Beltran, Floyd Landis, Roberto Heras of Spain and Tyler Hamilton - all former Postal riders during Armstrong's seven Tour wins from 1999-2005 - failed doping tests after quitting the Texan's team.

Some riders expressed dismay at the latest revelation of doping on the Tour.

"It's just amazing. It's irresponsible," British cyclist David Millar said. "This guy does not have any love or care for the sport.

"The unfortunate is that we are learning that things that look too good to be true are too good to be true," Millar added.

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AP Sports Writers Andrew Dampf in Rome and Jerome Pugmire in Lavelanet contributed to this report.

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