Hamburg - Retests of samples gathered at the Beijing Olympics and at the Tour de France could soon expose more doping offenders in sport.

The International Olympic Committee announced on Wednesday that the Beijing samples will be re-examined for forbidden substances, most notably the latest generation of the blood booster EPO, CERA (Continuous Erythropoiesis Receptor Activator).

Also on Wednesday, French anti-doping agency (AFLD) supremo Pierre Bordry said that suspicious 2008 Tour samples will soon undergo a retest for illegal own blood transfusions, on top of the CERA tests which are currently carried out.

Three Tour riders tested positive for CERA through a new blood test which was recently developed for this latest generation of the blood booster EPO: Riccardo Ricco, Leonardo Piepolo (both Italy) and Stefan Schumacher (Germany).

Ricco already tested positive for CERA at a urine test during the Tour and is banned from competition.

The new CERA test allows the IOC to retest its Olympic samples as well. The IOC conducted 4,770 doping tests around the August 8-24 Games in Beijing, 3,801 urine tests and 969 blood tests.

"The IOC intends to retest the samples collected this summer during the Olympic Games in Beijing. Substances that will be tested for across all sports include EPO CERA," IOC spokeswoman Emmanuelle Moreau told Deutsche Presse-Agentur dpa on Wednesday.

"All samples are currently being repatriated to the WADA-accredited laboratory in Lausanne where Olympic samples are usually stored after the Games. The details of the retesting procedure are currently being discussed with WADA."

Six athletes were caught doping during the Olympics and three others are under suspicion, with their cases still pending.

IOC vice-president Thomas Bach welcomed the retesting scheme, for which the date is yet to be given.

"It is a deterrent for every cheater and for every potential cheater as well. It is a great sign of determination for sport and shows that we are very serious about clearing up," said Bach.

Bach had warned on Tuesday that cycling could lose its place at the Olympics if there was no joint clean up effort, a statement that drew sharp criticism from world cycling body (UCI) supremo Pat McQuaid.

Echoing a similar pre-Olympic statement from IOC boss Jacques Rogge, Moreau said that the UCI has the backing of the IOC.

"The IOC will continue to support the UCI - and any other international federation - as long as it is deploying meaningful and credible means and efforts to fight against doping," said Moreau.

It was not known immediately whether the IOC retests will also include a currently developed test for illegal own blood transfusions - announced by Bordry in an interview with German ZDF television.

"We have already received strong indications of own blood doping cases. We won't be able to say until a later date whom that involves," Bordry said.

"Soon we will be able to detect own blood transfusions and we will then conduct the retests."

Around 30 riders had abnormal blood levels in tests carried out ahead of the Tour, with these riders targeted at the race and through the retests.

"Some of the suspected riders returned to their normal (blood) level (during the Tour). But we were surprised to see how weak their performance was," said Bordry. (dpa)