Spanish rider Moises Duenas of the Barloworld team has tested positive for the banned blood booster erythropoietin (EPO) during the Tour de France and banned products have been found in his room during a search, his team revealed on Wednesday.

The 27-year-old tested positive during the fourth stage, a 29.5 km time-trial at Cholet.

His team immediately withdrew him from the race before the 11th stage at Lannemezan, the third and final day of climbing in the Pyrenees.

A team spokesman from the British-registered team confirmed that police had taken Duenas away for questioning and said they had suspended the rider pending the results of further tests, adding the team had been testing the riders regularly, but had not noticed any anomalies.

Late afternoon, Barloworld issued a statement on the team website saying police had found banned products in the room of Duenas, a former winner of the Tour de l’Avenir – considered the ‘mini’ Tour de France. “Banned products which were absolutely not provided or prescribed by the team doctor were found in the room of Moises Duenas,” the statement read.

Barloworld manager Claudio Corti added: “I have asked French police to hold a full enquiry into the case to understand the seriousness of what Moises Duenas has done. “It seems he used banned products without the knowledge of anyone in the team.” Corti added he was stunned by the news. “I’m shocked. I want to find out more about what has happened before going into detail and taking further action. However, the one thing I will say is that 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 Spaniard, in his third Tour, had been in 19th position after the first ten stages, 6min 43sec behind Australian race leader Cadel Evans.

Duenas, who hails from the same town as triple Tour of Spain winner Roberto Heras, currently suspended for EPO use, becomes the second rider to fail a drugs test in this year’s race after compatriot Manuel Beltran of Liquigas also tested positive for EPO during the first stage.

Beltran, a former teammate of seven-time Tour winner Lance Armstrong, was held in custody overnight by police before returning home. His future will depend upon the results of a second B sample which, if it confirms the first test, will lead to his sacking by Liquigas.

All tests at the Tour are being carried out by the French national anti-doping agency (AFLD) because the race is being held under the auspices of the French federation.

That decision came in the wake of an ongoing feud between the International Cycling Union (UCI) and the company which runs the Tour, ASO (Amaury Sports Organisation).

The AFLD carried out approximately 60 random and targeted tests on French and foreign riders in the lead-up to the Tour from the 20 teams taking part in the race.

In the two days prior to the start, the AFLD took blood samples from all 180 riders. It was from one of those samples that suspicion arose regarding Beltran. He was targeted for a urine test on the first stage, the result of which confirmed he had used EPO.

AFLD chief Pierre Bordry said they had targeted Duenas deliberately for a urine test. “We had reason to look at him more closely,” Bordry told AFP. According to sources, however, Duenas was not one of the reported 10-20 riders whose blood parameters had prompted the AFLD to suspect them of doping.

While the news will be a further blow to the image of cycling, Frenchman Roger Legeay, who manages the Credit Agricole team, said it would ultimately prove the controls are working. “It’s not great to hear that a rider has cheated, but that’s what the tests are designed for. When you look, sometimes you find,” he said before the start of Tuesday’s 11th stage.