LONDON — The IOC's pursuit of drug cheats from the Beijing Olympics paid off today with confirmation that six athletes turned up positive for a new blood-boosting substance in retests of samples from last year's games.

The International Olympic Committee said a total of seven positive tests involving six athletes came back positive for CERA, an advanced version of the endurance-enhancing hormone EPO.

The IOC did not name the athletes or sports involved, saying it was notifying the athletes through their national Olympic committees. The Italian Olympic Committee said one of the positive samples belonged to one of its male athletes.

"The further analysis of the Beijing samples that we conducted should send a clear message that cheats can never assume that they have avoided detection," said Arne Ljungqvist, chairman of the IOC medical commission.

The IOC reanalyzed a total of 948 samples from Beijing after new lab tests for CERA and insulin became available following the Olympics. The testing began in January and focused mainly on endurance events in cycling, rowing, swimming and athletics.

"Due to the presumption of innocence, the IOC will not comment on any individual case," the IOC said.

The IOC will wait for word from the national Olympic bodies before holding any disciplinary hearings. Athletes found guilty of doping face being disqualified from the Olympics and stripped of any medals they won.

In the meantime, national and international bodies are free to impose provisional suspensions of athletes, the IOC said.

The Italian Olympic Committee said its athlete had been informed along with the committee's anti-doping prosecutor. Italian officials said they had not been authorized by the IOC to identify the athlete.

A Greek race walker, Athanasia Tsoumeleka, announced in January that she had tested positive in the new Beijing checks. Tsoumeleka, who finished ninth in Beijing in the 20K walk, was charged by a Greek prosecutor earlier this month with using banned drugs.

The IOC previously disqualified nine athletes for doping at the Aug. 8-24 Olympics. In addition, there were six doping cases involving horses in the equestrian competition.

The IOC is storing doping samples for eight years so they can be tested retroactively when new detection methods are developed.