Young Italian cycling star Riccardo Ricco has become the third rider on the Tour de France to test positive for the blood-booster EPO, the online edition of the daily L'Equipe reported.
The 24-year-old Ricco, who has won two stages in this year's Tour, was reportedly detected with traces of CERA (Continuous Erythropietin Receptor Activator) in his urine sample.
CERA is a so-called third-generation version of EPO - a protein hormone produced by the kidney which stimulates the production of red blood cells - with a longer half-life and was thought to be virtually undetectable.
The website of the Tour de France said that Ricco's Saunier Duval team had dropped out of the race on the news, leaving only 159 riders, of the 180 who started on July 5, in the race.
Ricco ranked ninth in the general standings, 2 minutes 29 seconds behind the leader, Cadel Evans of Australia. In spring, he placed second in the Giro d'Italia.
The report was made public one day after the announcement that EPO had been detected in the blood sample of the Spanish rider Moises Duenas taken after the race's fourth stage, on July 8.
Duenas was taken into custody by police on Wednesday and his Barloworld team later confirmed that a search had turned up banned substances in his hotel room.
L'Equipe reported that Duenas was presented to a judge in the city of Tarbes early Thursday and may be placed under investigation, a legal step preliminary to charges being filed.
Doping is a criminal offence in France and under stricter laws introduced shortly before the Tour can be punished with up to five years in prison.
Last week another Spanish rider, Manuel Beltran, was dropped from the race after traces of EPO were found in his blood following the first stage of the race, on July 5.