PARIS (Reuters) -- This year's Tour de France will be the most scrutinized sports event ever by anti-doping authorities, International Cycling Union (UCI) president Pat McQuaid said on Wednesday.
More than 500 tests will be carried out during the world's greatest stage race featuring 180 riders, with 50 of them set to undergo more tests than the others.
The 50 riders have been targeted because they are either top contenders or because their biological passports have raised suspicions in the UCI.
"The Tour de France will be the most tested event in the history of sports," McQuaid told a news conference, adding the UCI would work in collaboration with the French Anti-Doping Agency (AFLD). "It is enormous".
"The 50 riders were picked on a sporting basis, among the favorites of the Tour de France, and also from the knowledge we have got from the biological passport.
"What is important is not the number of tests, but the fact that we target riders," said AFLD president Pierre Bordry.
He added the names of the 50 riders would not be made public.
All riders will give two blood samples on Thursday, July 2, two days before the start, which will be analyzed and stored for possible further testing. UCI doctor Mario Zorzoli said eight to 11 riders would be tested every day.
Bordry said the UCI and the AFLD would work closely together to zero in on cheats following a first collaboration during the Paris-Nice stage race in March.
"I want to state that those who dope will have to be very careful because we will be extremely thorough," he said.
In October, 2007, the UCI and the World Anti-Doping Agency (WADA) announced they would collect blood samples from all professional riders to create a medical profile, or passport, that would be compared to the data registered in doping tests.
The Tour de France has been marred by doping scandals in the past three years.
In last year's edition, top Italian rider Riccardo Ricco was kicked out of the race after failing a test for the new generation of EPO called CERA (Continuous Erythropoiesis Receptor Activator).
Austrian Bernhard Kohl, third overall and the race's top climber, as well as Italian Leonardo Piepoli and German Stefan Schumacher were also found guilty of using CERA following retroactive tests carried out in September.