The athletes competed in three sports but will not be named until their 'B' samples have been analysed.
The eight are among the 23 athletes who tested positive in the retrospective testing of 265 samples from 2012.
Thirty-one athletes, 14 from Russia, failed tests when 454 samples from the 2008 Games in Beijing were retested.
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Russia has already been banned from international athletics competition by the sport's world governing body, after a World Anti-Doping Agency investigation revealed systematic doping among its athletes.
The International Association of Athletics Federations is set to meet on 17 June to decide whether they should be allow to compete in Brazil.
The retests from the 2008 and 2012 Games were targeted at athletes who could potentially participate in Rio.
The International Olympic Committee has said the re-analysis programme is ongoing, with the possibility of more results in the weeks to come.
Eight Russian athletes failed drug tests in the retesting of samples from the London 2012 Olympics, the Russian Olympic Committee has announced.