Cycling's governing body (UCI) admitted on Friday to drawing up a list in which it had estimated the 'doping risk' of each rider at last year's Tour de France but regretted the document had been leaked and thus made public.

French sports daily L'Equipe unveiled the doping suspicion index, in which riders are given a rating of suspicion scaling from 0: Not suspicious - to 10: Highly suspicious.

The UCI said the list is a working document helping to steer testing, not a list of riders who have done any wrongdoing.

"The document ... was meant for the UCI and independent observers of the World Anti-Doping Agency (WADA). We will investigate to see how such a document has leaked," a UCI spokesman said on Friday.

The average index of the 198 riders from the 2010 Tour de France is 2.434.

The index is a summary from the riders biological passport's data and a blood test carried out on July 1, two days before the start of the Tour.

UCI president Pat McQuaid declined to further comment.

Riders reacted angrily.

Before the start of the seventh stage of the 2011 Giro d'Italia former Giro leader David Millar of Team Garmin-Cervelo commented "heads should roll" at the UCI for allowing the leak.

"It's shocking. I understand that that list should exist, that's what targeted testing is about," the Briton said.

"This list should never have been released. The UCI, some of their people should be fired for this. A major investigation should go on into what exactly they are doing with this model."

Other team officials were also angered.

"It's an abuse of trust and it seems that anybody can filter what they like and the price gets paid by the riders, not by the guy who does the leak," Garmin sports director Bingen Fernandez told reporters.

"If it's confidential, it has to stay confidential. If somebody in a bank revealed the equivalent sort of details about bank accounts, they'd be sacked."

Millar, who was suspended for two years in 2004 after admitting he took a banned performance-enhancing substance, said he had a rating of 4 out of 10.

"I understand I'm number four because of my misdemeanours in the past," he said.

"But this (list) just does not add up."

Briton Mark Cavendish reacted angrily on his Twitter feed.

"So there's a leaked 1-10 'suspicion' scale for all 2010 Tour De France riders. So now EVERYONE'S suspicious, but just HOW suspicious?!" he wrote.

Australian Robbie McEwen added on Twitter: "I'm all for catching cheats but draw the line at this sort of thing which could be based on 1 single wayward statistic. And who leaked it??"

Three-times Tour winner Alberto Contador, who is waiting for the Court of Arbitration for Sport (CAS) to rule on his positive test for the banned anabolic agent clenbuterol, will not make any comment, his spokesman said.

"It is greatly to the UCI's credit that they give themselves the means to fight against doping," Cofidis manager Eric Boyer commented.

Tour de France director Christian Prudhomme told reporters: "It's is an additional tool in the fight against doping. It is because cycling is a forerunner in the fight against doping that such a list exists.

"I would not like the word 'suspicion' to be associated with the sport just because, precisely, it's been fighting against doping."