LONDON • Thirty-one athletes from six sports and 12 countries could be banned from August's Rio de Janeiro Games after the International Olympic Committee (IOC) retested 454 anti-doping samples taken from the 2008 Beijing Olympics.
The IOC said it had focused on athletes who may be going to the Rio Olympics.
The Lausanne-based body's executive board also announced that the results of 250 more retests from London 2012 would come shortly, with further retesting of medallists from 2008 and 2012 also planned.
"All these measures are a powerful strike against the cheats we do not allow to win," said IOC president Thomas Bach. "They show once again that dopers have no place to hide.
"The retests from Beijing and London, and the measures we are taking following the worrying allegations against the laboratory in Sochi, are major steps to protect the clean athletes irrespective of any sport or any nation. We keep samples for 10 years so that the cheats know that they can never rest."
His reference to the Sochi laboratory follows allegations of systematic cheating by Russia during the 2014 Winter Olympics.
This was strongly hinted at in the World Anti-Doping Agency (Wada)'s independent commission inquiry into doping within Russian athletics last year which had led to Russia's mighty track and field programme being sidelined.
A decision on whether the country will be reinstated for the Rio Olympics will be announced on June 17, with many anti-doping experts saying they have almost no chance of overturning their ban.
So far, most of the attention during the Russian doping crisis has been focused on the International Association of Athletics Federations, which covered up positive tests from Russia and elsewhere.
However, the IOC has come under increasing fire for saying so little about the growing evidence that this problem goes beyond athletics and beyond Russia.
The retesting of samples from previous Games is not a new policy, with anti-doping authorities usually waiting until the statute of limitations is about to kick in, so they can take full advantage of any developments in testing technology.
The statute of limitations in place for the Beijing Games was eight years, which means the IOC had until the end of the summer to look again. But the decision to press on with retesting from London looks very much like a response to the months of negative headlines that have engulfed Olympic sport.
With that in mind, it is telling that the IOC has also asked Wada "to initiate a fully-fledged investigation into allegations that testing at the Sochi laboratory was subverted".
It has asked the Lausanne laboratory that is storing all the samples from Sochi for 10 years to cooperate.
THE GUARDIAN, REUTERS