The Russian Olympic Committee has said 14 of its athletes at the 2008 Beijing Olympics tested positive for doping during re-tests of their samples.
In a statement (in Russian), it said it had received the information in “official documents” from the International Olympic Committee (IOC).
The IOC earlier said up to 31 athletes could be banned from the Rio Games.
The Russian Athletics Federation said any athlete found to have used doping in previous years would not go to Rio.
It said it took “such a tough decision” in order to do everything possible that only “clean athletes” could take part at the 5-21 August event.
On Thursday, the Russian Olympic Committee said it would not name 14 athletes from three sports disciplines until their B samples had been checked and official disciplinary proceedings had started.
It said this was in accordance with IOC anti-doping rules.
However, Russia’s Match TV revealed the names of all 14 athletes, saying they included 10 Olympic medallists.
It said that among them were Yulia Chermoshanskaya, who won gold in the 4x100m relay team, silver medallist javelin thrower Maria Abakumova and Anna Chicherova, who won bronze in the high jump.
Chicherova was also the gold medallist in London 2012.
Last week, the IOC announced that 454 selected doping samples from the 2008 Games had been re-tested.
The IOC said the re-tests were conducted using the very latest methods of scientific analysis.
Earlier this month, a whistleblower alleged Russian secret service agents helped to protect drug cheats at the 2014 Sochi Olympics, although the Russian authorities denied the claims.
The World Anti-Doping Agency (Wada) is now investigating those allegations and has appointed former Interpol agent and French Gendarmerie Major Mathieu Holz to lead the inquiry.
Russia was banned from athletics competition in November after a Wada commission report recommended the sanction.
Russian sports minister Vitaly Mutko said his country was “very sorry” and “ashamed” of cheating athletes who were not caught by its anti-doping systems.
But he argued not lifting the ban for the Rio Games would be “unfair and disproportionate” and that clean athletes should not be punished.
The decision on whether to admit Russian athletes to Rio is expected on 17 June.