Lausanne: The international sports tribunal on Thursday rejected an appeal by Russian athletes against a Rio Olympics ban amid mounting pressure for action over state-run doping in Russia.
The Court of Arbitration for Sport (CAS) ruling on track and field is seen as a key indicator as the International Olympic Committee (IOC) debates whether to order a blanket ban on Russia from the Rio Games that start August 5.
The IOC executive is to hold more talks on Sunday and a decision on a ban could be announced after, an Olympic spokesperson said.
The heads of international federations for the sports in Rio held their own talks on Thursday.
Russia reacted angrily however. It is a sporting powerhouse whose absence from Rio would create the biggest crisis in decades for the Olympic movement.
But there have been widespread calls for exemplary sanctions against the state orchestrated campaign.
"This will scare a lot of people, or send a strong message that the sport is serious about cleaning up," six-time Olympic sprint title winner Usain Bolt of Jamaica said of the CAS ruling.
Russia's Sports Minister Vitaly Mutko called the CAS ruling "politicised" and illegal however.
CAS said it had unanimously "dismissed" an appeal by the Russian Olympic Committee and 67 athletes against an International Association of Athletics Federations (IAAF) ban.
The 67 included two time Olympic pole vault champion Yelena Isinbayeva and world champion men's 110m hurdler Sergey Shubenkov.
The IAAF ban covers all international competition and follows an investigation by the World Anti-Doping Agency last year which found widespread "state-sponsored" doping.
Isinbayeva slammed the CAS ruling as a "funeral for athletics" and "a blatant political order."
The Kremlin expressed "deep regret" over the decision and said it had "no legal basis." Russia has denied any state involvement in the doping crisis.
Originally, 68 Russians had appealed against the IAAF ban but the governing body has cleared US-based long jumper Darya Klishina to compete in Rio.
An IOC ethics commission is to rule on the case of Yuliya Stepanova, an 800m runner who turned whistleblower on the doping.
The IAAF welcomed the CAS tribunal ruling.
"Today's judgement has created a level playing field for athletes," said an IAAFstatement.
"The CAS award upholds the rights of the IAAF to use its rules for the protection of the sport (and) to protect clean athletes."
The CAS ruling has been the focus of Olympic attention, however, since an independent WADA report this week said Russia ran a "state-dictated failsafe system" of drug cheating in 30 sports at the 2014 Sochi Games and other major events.
IOC president Thomas Bach has called Russia's actions a "shocking and unprecedented attack on the integrity of sport and on the Olympic Games."
According to a report released this week by Canadian lawyer Richard McLaren, the doping included the switching of Russian samples by secret service operatives at the 2013 world championships in Moscow.
It said the operation was directed by the sports ministry, with help from the FSB intelligence agency.
WADA, backed by the United States and other nations, has called for Russia to be completely banned from the Rio Games.
The IAAF suspended Russia in November after an inquiry which first spoke of "state sponsored" doping.
It refused to lift the suspension last month, meaning no Russian athletes could take part in Rio.
Russia was the second most successful athletics nation at the 2012 London Olympics, behind the United States, with seven gold medals, four silver and five bronze.
Originally, Russia had 17 medals. But several have already been lost or are at risk because of doping failures.
Olympic 3,000 metre champion Yulia Zarapova has tested positive for anabolic steroids and will almost certainly be stripped of her gold medal.
Woman's discus thrower Darya Pishchalnikova, silver medallist in London, has been banned for 10 years because of drug failures.
The IOC has not yet reconfirmed the results of the London Olympics following the retesting of doping samples.
IAAF president Sebastian Coe welcomed the CAS ruling but said: "This is not a day for triumphant statements.
"I didn't come into this sport to stop athletes from competing. It is our federation's instinctive desire to include, not exclude."
He said that after the Rio Games an IAAF task force "will continue to work with Russia to establish a clean safe environment for its athletes so that its federation and team can return to international recognition and competition."