The International Olympic Committee (IOC) will appeal to Switzerland's supreme court against rulings which cleared some Russian Olympic athletes of doping sanctions.
The Olympic body is "not satisfied at all" by the verdicts and written explanations from the Lausanne-based Court of Arbitration for Sport, IOC President Thomas Bach saidexternal link on Thursday after an executive board meeting.
The Swiss Federal Courtexternal link, also based in Lausanne, can overturn CAS verdicts if legal process was abused, though appeals rarely succeed.
"The chances of winning did not play a role in our discussion," Bach said at a news conference. "The only factor which led us to this decision was the protection of the clean athletes who have finished behind the Russian athletes who have not been declared innocent."
Days before the Pyeongchang Winter Olympic Games in February, two CAS judging panels upheld appeals of 28 Russian athletes against IOC sanctions that included Olympic life bans and being stripped of their 2014 Sochi results.
CAS said the IOC's investigations in those cases did not prove doping offences, while also stressing the 28 were not formally declared innocent of taking part in orchestrated cheating.
Bach said on Thursday the IOC had "put ourselves into the shoes" of athletes who would want the Russian appeal victories evaluated again. A further 11 Russians lost their appeals at CAS, which confirmed their Sochi disqualifications.