(CNN) - The International Olympic Committee will use newly developed drug testing procedures to retest samples taken from athletes at last summer's Beijing Olympic Games, the IOC said Tuesday.

The new drug testing procedures will allow the IOC to test for two banned substances known to have been used in the past by athletes in endurance events like cycling, rowing, swimming and athletics, the IOC said.

The first substance is EPO CERA, a new version of the endurance-enhancing hormone EPO. Use of the substance was discovered during this year's Tour de France, and the World Anti-Doping Agency (WADA) then developed a blood test to test for it, the IOC said.

The second substance is insulin, a hormone that can enhance performance by influencing the glycogen metabolism. While the substance is not new, it wasn't until recently that a WADA lab developed an effective urine test for it, IOC spokeswoman Emmanuelle Moreau told CNN.

"Labs were looking for an efficient test, but the fully validated test was not available until very recently," she said.

The IOC will begin testing the Beijing samples at its labs in January, with results expected at the end of the first quarter of 2009, the IOC said.

There is no evidence that Beijing athletes were using either substance, Moreau said. The IOC simply tests for substances when new procedures to look for them are developed.

"When we have a test available which is fully validated, we use it and we don't hesitate to test retroactively," Moreau said.

Anticipating advances in technology, the IOC routinely keeps samples collected during each Olympic Games for eight years. It allows the Olympic Committee to analyze samples retroactively should new tests to detect new substances and doping methods become available.

Authorities carried out some 4,770 doping tests in Beijing as part of the largest-ever testing program for an Olympic Games, the IOC said. As a general rule, the top-five finishers in an event, plus a further two selected randomly from the finish list, were tested.

If any of the samples test positive for the banned substances, the athletes could lose their medals or rankings from the Games, or face expulsion by sports governing bodies.

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