Thirty one athletes from six sports could be banned from this year's Rio de Janeiro Olympics after 454 doping samples were re-tested from the 2008 Beijing Olympics, the IOC said on Tuesday.
A statement from the International Olympic Committee said its Executive Board had stepped up the fight against drugs cheats and the re-tests had been carried out in conjunction with the World Anti-Doping Agency (WADA) and international federations.
It said the re-tests were focused on athletes who could potentially take part in the Rio Games this year.
Twelve national Olympic associations would be informed in the coming days, the IOC said.
Another 250 samples would be re-tested from the London 2012 Olympics.
"The aim is to stop any drugs cheats coming to the Olympic Games in Rio de Janeiro," the IOC said.
