Doping retests have found banned substances in 45 athletes from the Beijing and London Olympic Games.
Of the 30 in Beijing, 23 were medallists, the International Olympic Committee said.
The reanalysis of the tests are part of the IOC’s efforts to keep dopers away from the Olympic Games Rio 2016.
"All athletes found to have infringed the anti-doping rules will be banned from competing at the Olympic Games Rio 2016," the IOC said.
Russia's banned track and field athletes are expected to find out whether they will be allowed to compete in the Rio Olympics Games.Read the full story ›
A series of re-testing and an investigation will take place into Russian athletes who took part in the 2014 Olympics Winter Games in Sochi.
Coaches, officials and support staff will be put under the microscope, following the McLaren Report into widespread manipulation of doping tests.
The IOC will initiate reanalysis, including forensic analysis, and a full inquiry into all Russian athletes who participated in the Olympic Winter Games Sochi 2014 and their coaches, officials and support staff. For this purpose, a specific Disciplinary Commission is set up under the chairmanship of Mr Denis Oswald. Following the report of this Commission, the IOC EB will impose all the appropriate sanctions.
The International Olympic Committee have delayed their decision on whether to ban all Russian athletes from Rio 2016 until Friday.
An appeal against a previous sanction against Russia will be heard on Thursday by The Court of Arbitration for Sport.
The IOC say they will "explore the legal options with regard to a collective ban of all Russian athletes for the Olympic Games 2016 versus the right to individual justice".
With regard to the participation of Russian athletes in the Olympic Games Rio 2016, the IOC will carefully evaluate the IP Report. It will explore the legal options with regard to a collective ban of all Russian athletes for the Olympic Games 2016 versus the right to individual justice. In this respect, the IOC will have to take the CAS decision on 21 July 2016 concerning the IAAF rules into consideration, as well as the World Anti-Doping Code and the Olympic Charter.
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The World Anti-Doping Agency is calling for a ban of Russian athletes at the Rio Games after state-sanctioned doping was revealed.Read the full story ›
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Russian long jumper Darya Klishina has been cleared to compete as a "neutral" athlete at the Rio Olympics, the IAAF has announced.
Athletics' world governing body said in a statement that the 25-year-old, who trains at the IMG Academy in Florida, had become the second athlete to meet its "exceptional eligibility criteria".
But Russian news agency TASS said all other applications from Russian athletes, including pole vault great Yelena Isinbayeva, had been rejected.
The head of the legal department at the Russian Olympic Committee, Alexandra Brilliantova, was quoted by TASS as saying: "The refusals were received by everyone, except for Klishina."
US Open champion Dustin Johnson has become the latest golfer to withdraw from the Olympics over fears of the Zika virus.
Several players including world number one Jason Day and four-time Major winner Rory McIlroy have already pulled out of Rio 2016 citing worries over the virus and Johnson has become the first American to do so.
Zika is a mosquito-borne virus which has been linked to defects in newborn babies.
"As an athlete, I can think of no greater honor than representing the United States in the Olympic Games," Johnson said in a statement released by his agent David Winkle.
"However, after much careful consideration and discussion with both my family and my team, I have made the decision to withdraw from the 2016 Olympic Games."
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