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

A person familiar with the test results said the tests nabbed three track and field athletes, two cyclists and one weightlifter. The IOC did not name the athletes or sports involved, saying it was notifying the athletes through their national Olympic committees.

The person, speaking on condition of anonymity because the names haven't been released by the IOC, said one of the track and field athletes was a male gold medallist. The other medalist was in cycling.

The Italian Olympic Committee said one of the six was an Italian athlete. The Italian news agency ANSA identified him as cyclist Davide Rebellin, silver medallist in the road race.

US Olympic Committee spokesman Darryl Seibel said the federation hadn't received notification from the IOC of any adverse findings involving a US athlete.

"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 reanalysed 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.