Russians and Belarusians who qualify in their sports for the 2024 Paris Olympics can take part as neutrals without flags, emblems or anthems.
The nations were initially banned from competing internationally, after Russia's invasion of Ukraine last year, with Belarus used as a staging ground for the attack.
In March, the International Olympic Committee issued a first set of recommendations for international federations to allow Russian and Belarusian competitors to return, and they have since done so in most events.
Athletics - the Games' biggest sport - is unlikely to open the door for them to return, after banning them following the invasion and sticking to it.
Ukraine Foreign Minister Dmytro Kuleba has condemned what he says is a "shameful" IOC decision, while Russian Sports Minister Oleg Matytsin has called the IOC conditions "discriminatory."
The neutral athletes will only compete in individual sports and no teams for the two countries will be allowed. Athletes who actively support the war in Ukraine are not eligible, nor are those contracted to the Russian or Belarusian military.
The IOC also says no Russian or Belarusian government or state official will be invited to or accredited for Paris 2024, but athletes should not be punished for the actions of their governments.
While Paris Games organisers have "taken note" of the IOC decision, it has drawn angry responses from Ukraine and Russia.
"The IOC essentially gave Russia the green light to weaponise the Olympics, because the Kremlin will use every Russian and Belarusian athlete as a weapon in its propaganda warfare," tweeted Ukraine's foreign minister Kuleba.
"I urge all partners to strongly condemn this shameful decision, which undermines Olympic principles."
Ukraine acting sports minister Matviy Bidnyy says his country's participation at the Paris Games will be decided after talks with the political and sports leadership.
"Regarding Ukraine's participation in the 2024 Olympic and Paralympic Games, we will make a decision later, after consulting with the Ukrainian sports community and the country's top political leadership," said Bidnyy.
Russian Sports Minister Matytsin says the IOC's approach is "unacceptable".
"Participation in the Olympics is an athlete's dream, but the conditions are discriminatory and go against the principles of sports," he was quoted by TASS news agency.
"By doing so, they harm the Olympic Games themselves and not Russian sports. The approach is absolutely unacceptable."
Of 4600 athletes who have qualified for the Games so far, eight are Russians and three hold Belarusian passports. More than 60 Ukrainians have qualified.
Reuters
