The International Olympic Committee reported 45 new doping failures on Friday from the 2008 Games in Beijing and London 2012, bringing the total number of positive drug test to 98 since a retesting programme was launched.
The IOC, facing one of its worst ever doping crises that could see sporting powerhouse Russia banned from the Rio Games, has reanalysed more than 1,200 samples, with the emphasis on medal winners.
Reporting results from its second wave of retests, the IOC said there were 30 "Provisional Adverse Analytical Findings" from competitors in Beijing 2008 and 15 "Adverse Analytical Findings" among London 2012 Olympians.
Within the Beijing group, 23 were medallists, the IOC said. The 30 positive results came from eight countries and four sports.
The second wave of retests from London included 138 samples. The 15 positive tests were from nine countries and two sports.
The IOC said it was not able to identify the athletes concerned, citing legal reasons.
"The new reanalysis once again shows the commitment of the IOC in the fight against doping,” Olympics president Thomas Bach said in a statement.
The IOC has said the retesting programme followed "intelligence-gathering" that began last year.
The new results may pile more pressure on the IOC as it faces making the unprecedented move of banning an entire country from a Games over doping.
Two reports from the World Anti Doping Agency have detailed rampant, state-run drug cheating by Russia, affecting 30 sports.
Russia's track and field team has already been banned from Rio by governing body IAAF.
But a dozen global anti-doping agencies and several national Olympic committees have urged the IOC to take exemplary action and rule all Russian competitors ineligible for the Rio Games, which start in two weeks.
The IOC said a decision could be made on Sunday.
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