The International Olympic Committee has retested 454 anti-doping samples taken from athletes at the 2008 Beijing Olympics, catching 31 cheats from six different sports and 12 countries.
The IOC said it had focused on athletes who were still active and therefore may have gone to the Rio Olympics this summer.
The Lausanne-based body’s executive board announced that the results of 250 more re-tests 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 re-tests from Beijing and London and the measures we are taking following the worrying allegations against the laboratory in Sochi are another major step 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.”
Bach’s 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’s independent commission inquiry into doping within Russian athletics last year, a damning report that led to Russia’s mighty track and field programme being sidelined.
A decision on whether they will be reinstated for the Rio Olympics will be announced on June 17th, with many anti-doping experts saying they have no chance of overturning their ban.
So far most of the attention during the Russian doping crisis has been focused at the International Association of Athletics Federations, which covered up positive tests from Russia and elsewhere, and Wada.
But 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 is surely 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”.
Dick Pound, the man who led the initial investigation into Russian athletics, has repeatedly said he was willing to go back into Russia to extend his investigation if the IOC or Wada would sanction and pay for it.
The IOC has asked the Lausanne laboratory that is storing all the samples from Sochi for 10 years to cooperate with the new inquiry and has placed its medical chief Dr Richard Budgett, a rowing gold medallist for Great Britain at the 1984 Olympics, at their disposal.
As well as doping, the Olympic movement has had to deal with reports of corruption around the decision to award the 2020 Games to Tokyo in recent weeks.
The executive board said it noted the response from the Japanese Olympic Committee and the former head of the Tokyo 2020 bidding committee to those reports and it would “continue to work to shed full light into the issue”.
The matter — an alleged bribe paid to former IAAF chief Lamine Diack via a middleman’s bank account — is currently under investigation by the French authorities, with the full cooperation of IOC’s own ethics panel.
