The International Olympic Committee (IOC) says that all Russian and Kenyan athletes who want to take part in the Rio Summer Olympics must be declared "clean" of doping by world sports federations.
IOC President Thomas Bach said after a special Olympic summit in Lausanne, Switzerland, on June 21 that the measure is being introduced because the Russian and Kenyan anti-doping agencies are unreliable and put "very serious doubts on the presumption of innocence" of athletes from those two countries.
Bach added that athletes who proved they are "clean" and certified by the governing bodies of individual sports would be allowed to compete in the Rio Olympics under their national flags.
That ruling contradicts a June 17 statement by the IAAF, the world track-and-field governing body, saying that any such athlete could only compete under a "neutral" flag, possibly the five-ring Olympic flag. The IOC endorsed the IAAF upholding its Olympic ban on the Russian track team, however.
Russian Sports Minister Vitaly Mutko said Russia is ready to fulfill all of the IOC conditions necessary for participating in the Rio Olympics.
"We will be doing everything that [the IOC] will be telling us," he said at the conclusion of the IOC summit, convened to ensure a "level playing field" for athletes competing in the Summer Olympics, to be held from August 5 to August 21.
Russian Olympic Committee head Aleksandr Zhukov, who attended the summit in Lausanne, said afterward that Russia will not boycott the Rio Olympics, as some reports had suggested Moscow might do.
But he said Russia will consider filing a lawsuit against the IAAF.
The anti-doping agencies of Russia and Kenya were found several months ago by the World Anti-Doping Agency (WADA) to be noncompliant and were decertified.
Bach also said the IOC fully respects the IAAF's decision to ban Russian track-and-field athletes from the Summer Olympics unless they show they have not taken part in doping.
The IOC also said it recognized "the enormous efforts and professionalism of…the Russian Olympic Committee."
That statement contrasts with a WADA report in November that found a "systematic and deeply-rooted culture of doping" in Russia that the agency said was state-supported.
The IOC is awaiting the results of dozens of retested urine samples from the 2014 Winter Olympics held in Russia's resort city of Sochi along with an investigative report by Canadian lawyer Richard McLaren to determine if Russian state officials were involved in covering up doping by athletes at Sochi.
Grigory Rodchenkov, who was fired as head of Russia's drug-testing lab in December, detailed in May what he said was an elaborate system by Russian officials – including state security agents – to exchange tainted urine samples of Russian athletes for clean ones during the 2014 Sochi games.
McLaren said on said on June 17 that his findings thus far support allegations that the Russian Sports Ministry was complicit in manipulating doping tests of Russian athletes before, during, and after the world track-and-field championships in Moscow in 2013.
McLaren's report is due to be made public by July 15.
If widespread involvement in doping by Russian officials is found, there is the possibility that Russian athletes in all sports could be banned from participating in Rio.
Former WADA President Dick Pound said on June 19 that such an action was possible, but he called it the "nuclear option."
Russian officials from Mutko to President Vladimir Putin have rejected charges of state involvement in doping and have said blanket bans on its athletes are unfair because they punish "clean" athletes.
Yelena Isinbayeva, a Russian pole vaulter who has won two Olympic gold medals and three world championships, has threatened to file a lawsuit against the IAAF for banning Russian track athletes from the Olympics.
Isinbayeva, who says she is drug-free, said the IAAF ban violates her human rights.
Russian officials have bristled at the possibility of whistle-blower Yulia Stepanova -- an 800-meter runner who has served a two-year ban for doping -- competing in Rio.
Stepanova, who along with her husband gave information to WADA about the extent and manner of doping in Russia, has said she would be open to competing in Rio despite no longer being a part of the Russian track-and-field team.
Rodchenkov, Stepanova, and her husband have all moved to the United States for security reasons.
With reporting by AP, AFP, and TASS