While many commentators praised what they said looked like a doping-free Tour de France, the head of the French anti-doping agency AFLD, Pierre Bordry, said he suspects riders are still using performance-enhancing substances or methods.

Bordry told French daily Le Monde that medicines were found in some of the trashcans of some teams.

"We found several strong medications, including a substance which produces insulin and is normally used for diabetes," he said.

After Sunday's Tour finish without a since positive doping test, headlines were largely positive about a race not tainted by doping substances. Headlines appeared such as "Drugs war is being won" or "Tour chief hails clean race," but Bordry is not convinced.

He said he believes that riders are having autologous blood transfusions and that two new types of doping substances were possibly used in the race, including one that has the same effect as EPO, and another which increases strength and burns fat.

Bordry says methods for detecting the substances could be developed by the fall.

Too lax?

Bordry was outspoken during the tour on the subject of doping which ruffled some feathers.

Detection methods for new performance-enhancing drugs will be ready this fall

Bordry had accused the International Cycling Union (UCI), which was in charge of testing, of being too "lenient." He made the criticism after anti-doping officials were kept waiting for nearly an hour by the Astana team in Andorra last week during an early-morning doping control. Both tour winner Alberto Contador and Lance Armstrong, who took third place, rode for the Astana team.

"This is the Tour de France and you can't wake up guys on a day of a mountain stage at 6am," said Lance Armstrong after Astana was criticized over the wait.

The French anti-doping agency also announced it will retest some blood samples from 14 riders in last year's Tour de France in September and October, looking mainly for the banned blood-booster CERA.

"Bordry's ego has gotten too big. He needs to come with facts or stay out of it," said Gerry van Gerwen, head of the Milram team.

Can doping be beat?

After the race ended on Sunday, Tour de France director Christian Prudhomme said he was pleased that no positive drug tests had returned, but he said the fight against doping in professional cycling is far from over.

"We can't allow ourselves to believe that things have completely changed, this is a fight that will go on and on," he said.

Tour winner Alberto Contador says he race a clean race

While some commentators breathed a sigh of relief that the Tour was not dragged through the doping mire this year as it was in 2008, others seemed resigned to the presence of a continual cat-and-mouse game of performance-enhancing drugs - their use, disguise and discovery.

"The only surprising thing is that there are still doped athletes who are dumb enough to throw proof of their illegal activities into the trashcan," wrote Arnd Festering in the German daily Frankfurter Rundschau.

"That's the only exciting thing: not whether any one used performance-enhancing drugs, but whether anyone was found out and who it was."

jam/dpa/AFP

Editor: Neil King