France’s national anti-doping agency (AFLD) is to begin retroactively testing blood samples from riders at this year’s Tour de France in a bid to find a type of EPO which is notoriously difficult to find.

AFLD chief Pierre Bordry said the test used to catch disgraced Italian Riccardo Ricco, whose urine samples tested positive for CERA at this year’s race, has now been replaced with a more effective blood test.

Among the samples set to be tested at the Chatenay-Malabry laboratory near Paris this week will be those of Italian rider Leonardo Piepoli, who was part of Ricco’s Saunier Duval team which was forced off the Tour after the latter’s positive test.

Despite four riders failing drugs tests at this year’s race, the AFLD claim that deterrents – including targeting suspect riders prior to competition – are working.

Spanish duo Manuel Beltran, of Liquigas, Barloworld’s Moises Duenas, Italian star Ricco and Dmitri Fofonov, of Credit Agricole, were all thrown out of the Tour.

Prior to the 2008 Tour, where the anti-doping controls were cranked up a notch, the AFLD took pre-race blood samples from around 30 riders deemed suspect.