The International Olympic Committee on Friday reported 23 new doping failures from the 2012 London Games and warned that more could be revealed in coming weeks.
The 23 were from six countries and took part in five different sports at the London Games. The IOC also said a 32nd suspected case from the 2008 Beijing Olympics has been detected.
The IOC said 265 samples from the London Olympics were retested “based on intelligence-gathering that began in August 2015.
“The reanalysis programme is ongoing, with the possibility of more results in the coming weeks,” the IOC said. The global body refused to say whether the new results would be from London or another event.
A total of 454 samples from Beijing have been retested.
The IOC said last week that 31 had failed doping tests. But its new statement said a 32nd case had shown “abnormal parameters” with further investigation pending.
The IOC should soon start giving the identities of athletes who failed tests in London on Beijing, or both. Russia has already acknowledged that 14 of the cases from Beijing involved Russian competitors.
All found to have taken banned performance-enhancing drugs will be banned from the Rio de Janeiro Games which start on August 5.
“These reanalyses show, once again, our determination in the fight against doping,” IOC President Thomas Bach said.
“We want to keep the dopers away from the Olympic Games in Rio de Janeiro,” he added. “This is why we are acting swiftly now.”
The IOC began re-testing samples amid mounting doping scandals last year, many with Russia at the centre.
The International Association of Athletics Federations suspended Russia in November after a World Anti-Doping Agency (WADA) report said there had been “state-sponsored” doping by Russian athletics.
The IAAF will decide on June 17 whether to readmit Russia so that its track and field competitors can take part in the Rio Games.
WADA is also now investigating claims by the former head of the Moscow anti-doping laboratory Grigory Rodchenkov that Russian secret service and government officials subverted samples at the Sochi 2014 Winter Olympics to cover up failures by Russian competitors.
Russia has denied any wrongdoing. But the scandals have increased pressure for tough action.
Olympic high jump champion Anna Chicherova has revealed that she was among competitors to have been informed of a failed test.
Chicherova said she was in “complete shock” and could not explain the positive test.
Second tests on the Beijing samples are due to be carried out on Tuesday and Wednesday at the IOC accredited Lausanne anti-doping laboratory. The identities of those who failed tests could be revealed by the end of the week or from June 5.
Martial Saugy, head of the Lausanne laboratory, told AFP that detecting equipment is much more “sensitive” to banned substances making it easier to catch dopers.
“This means the average detection window, which was six days, has gone to 20 or 30 days.” This is especially the case for anabolic steroids.
Technology has also improved for detecting blood doping, he said.