The Women's World Boxing Championships began in India on Thursday with several nations boycotting because of the presence of Russians and Belarusians competing under their flags.
Numerous international sports federations have banned Russian and Belarusian athletes from competition since Moscow's invasion of Ukraine last year.
Some sports have allowed them to compete but said they must do so under neutral flags.
But the International Boxing Association (IBA) event in Delhi involves fighters from both nations competing under their national flags and anthems.
The flags and colours of Russia and its political ally Belarus were paraded at Wednesday's opening ceremony.
The IBA is headed by Russian Umar Kremlev and counts Russian energy giant Gazprom as a major financial backer. The IBA was suspended by the International Olympic Committee in 2019 over multiple corruption scandals.
The United States, Ukraine, Canada, Sweden and Britain are among the countries boycotting the tournament, which runs until March 26 and involves 65 nations.
Some have said they will also refuse to take part in the men's event in Tashkent, Uzbekistan on May 1-14.
GB Boxing said last month that the IBA's move to allow boxers from Russia and Belarus to compete in India under their national flags defied IOC resolutions.
"This has put further distance between IBA and the Olympic movement in addition to the significant, longstanding issues over sporting integrity... which the IOC has asked IBA to address," a statement said.
'Discrimination'
Russia's Sports Minister Oleg Matytsin said that "in this difficult period it is important that the team appears under the Russian flag... You can see that these young girls know which country they are representing.
"Sport should be separate from politics and should not be the target of discrimination on the basis of nationality," Matytsin said Tuesday while in New Delhi, quoted in a statement by his ministry.
The IOC suspension of the IBA means that boxing risks disappearing as an Olympic sport from the Paris Games in 2024.
The French Boxing Federation is allowing its fighters to compete in Delhi, with its head Dominique Nato saying Tuesday it wanted to remain "neutral" ahead of the Paris Olympics.
"I am aware of what is happening in the world, but again, politics is taking sport hostage and that is unacceptable," Nato told AFP.
Boxers from other European Union nations including Spain and Italy were taking part, according to organisers, as well as New Zealand, Australia and Japan.
On March 1 the IBA opened disciplinary action against the chiefs of several national boxing associations over the boycott, accusing them of "unethical behaviour".
"In boxing, there is no place for any form of discrimination and IBA sees it as its mission to protect its values," it said.
Russia has 12 boxers at the tournament and Belarus six.
"It is very important for me to represent my country under my flag and I will proudly do it," Russian boxer Ekaterina Paltseva told AFP.
"In my opinion, there should be no (politics) in sports. Sports must combine all countries."