The threat of being caught cheating at this year’s Tour de France has proved a major deterrent, according to the chief of France’s national anti-doping agency (AFLD) on Tuesday.

AFLD chief Pierre Bordry said prior to the race’s 16th stage from Cuneo, Italy to here that he had no further positive cases to report in the wake of three positive tests for EPO.

His claims come in the wake of a newspaper report in which disgraced Italian climber Riccardo Ricco re-affirms that he did not use banned substances.

Ricco is one of three riders to have been forced off the race after testing positive for the banned blood booster EPO (erythroipoietin).

His Saunier Duval team, who have since sacked him, pulled out the day his positive test, from the fourth stage time trial, was revealed.

Ricco denied ever taking banned substances last week in an interview with Italian media. He is reported in Le Monde newspaper to have told French police while in custody: “I did not take EPO. All the products that I’ve used were prescribed to me either by the Spanish doctor who works with my team, although I don’t know his name. “I maintain, as I have said before, that I did not take any banned substances.”

Ricco faced charges of possession and use of banned substances, which is against French law, when he appeared in a French court last week.

He has since returned to his native Italy. Bordry had warned before the first stage that the AFLD would be specifically targeting riders with suspect blood profiles – samples were taken from all 180 riders before the start. And he said that after all were analysed, he believed that “most of the samples we’ve dealt look normal … It appears that efforts are being made, and that the pressure we’ve applied has had an effect.”

Bordry said however he did not yet have the results of further analyses on samples from Italian Leonardo Piepoli, who was also sacked by Saunier Duval for suspected doping, despite not testing positive. “I still don’t have the results of his tests. Right now I have no positive doping cases to report.”

Spaniards Manuel Beltran, of Liquigas, and Moises Duenas, of Barloworld, also tested positive for EPO although both of their teams remain at the Tour.