CAS, sport's highest tribunal, rejected on Thursday Russia's appeal against a doping ban for its entire athletics team from the Rio Olympics
The Kremlin said on Friday that Russia had limited time for "legal manoeuvring" to defend the rights of its athletes after a decision by the Court of Arbitration for Sport (CAS) on Thursday.
"Certainly, the court decision was unpleasant and bad news," Kremlin spokesman Dmitry Peskov told a conference call with journalists.
"To our regret, that decision falls on the eve of the Olympics, so of course legal manoeuvring to continue defending the rights of our sportspeople is pretty limited in time now."
CAS, sport's highest tribunal, rejected on Thursday Russia's appeal against a doping ban for its entire athletics team from the Rio Olympics.
Russia had argued it had taken steps to clean up the sport, and that the blanket ban was unfair to individual athletes with no record of doping.
Russian officials, and many ordinary people in the country, have interpreted the doping allegations as part of a conspiracy inspired by Western governments who fear Moscow's growing influence.
A spokeswoman for the Russian Foreign Ministry called the court decision "a crime against sport".
The decision by the Swiss-based court increases the possibility that the International Olympic Committee (IOC) will now exclude Russia from all sports, not just track and field, in Rio de Janeiro. The IOC is expected to reach a final decision on Sunday.
That would mark the deepest crisis in the Olympic movement since the U.S. and Soviet boycotts of the 1980s, and would be a grave blow to a nation that prides itself on its status as a sporting superpower.
Russia is one of the world's foremost sporting powers which won the third biggest overall medal haul at the last summer Olympics in 2012 -- though some of those results are now in question because of doping suspicions.