Ukraine's sports minister warned on Thursday his country could boycott the 2024 Paris Olympics if Russian and Belarusian athletes are allowed to take part.
The International Olympic Committee (IOC) said on Wednesday it was seeking a "pathway" for Russians to take part in the Games despite the invasion of Ukraine.
Ukraine's sports minister Vadym Goutzeit said such a move was "unacceptable."
"Our position remains unchanged – as long as the war continues in Ukraine, Russian and Belarusian athletes should not be in international competitions," Goutzeit wrote on Facebook.
"If we are not heard, I do not exclude the possibility that we will boycott and refuse to participate in the Olympics."
Russia and its ally Belarus have been sidelined from most Olympic sports since Russian forces invaded Ukraine last February.
Ignoring calls from Ukraine to ban Russian and Belarusian athletes from next year's summer Olympics, the IOC said Wednesday that a way to allow competitors from those countries to take part as neutrals should be "further explored."
The IOC said "no athlete should be prevented from competing just because of their passport."
Following that announcement, the Olympic Council of Asia on Thursday offered athletes from both countries the chance to compete in this year's Asian Games.
That is a significant move because they could gain qualifying marks in competition in Asia to allow them to compete in Paris.
The IOC's stance was strongly criticised by Britain and Denmark on Thursday.
Britain, which has supplied military and humanitarian support to Ukraine since the invasion began, said the IOC's move was a "world away from the reality of war."
Britain's Culture Secretary Michelle Donelan said: "We condemn any action that allows President Putin to legitimise his illegal war in Ukraine.
"This position from the IOC is a world away from the reality of war being felt by the Ukrainian people – and IOC president (Thomas) Bach's own words less than a year ago where he strongly condemned Russia for breaking the Olympic Truce and urged it to 'give peace a chance'," she added.
The head of Denmark's National Olympic Committee said his country was also strongly opposed to Russia returning to the Olympic fold.
"The Russian aggression in UKR is escalating," Hans Natorp tweeted. "Under these circumstances, it will be unacceptable to open up for RUS and Belarusian international sports participation.
"We stand firmly in our position. Now is not the right time to consider their return."
The mayor of Paris said however she was in favour of Russian athletes competing at the 2024 Games, providing they did so as neutrals.
"I think that it's a sporting moment and we shouldn't deprive athletes of the competition," Anne Hidalgo told France 2 television on Thursday.
"But I think and what I'm arguing for, as is a large part of the sporting world, is that there isn't a delegation under the Russian banner."
She suggested they compete under a "neutral banner."
Paris organisers have no say on the participation of Russian and Belarusian athletes.
The IOC said on Wednesday that the international federation for each Olympic sport was "the sole authority for its international competitions."