Professional boxing's British governing body said on Thursday it would not allow boxers registered or licensed in Russia and Belarus to fight in Britain.
The British Boxing Board of Control's (BBBofC) statement follows global sporting sanctions in response to Russia's invasion of Ukraine.
A BBBofC statement on Thursday read: "Please note, the British Boxing Board of Control will not permit Boxers registered/licensed by the Russian Boxing Federation or Belarussian Federation of Professional Boxing to compete in the United Kingdom under the jurisdiction of the BBBofC at this time."
No major professional fights in Britain are currently scheduled involving boxers from Russia or Belarus.
Russian light-heavyweight world champion Dmitry Bivol is due to fight Mexican Saul "Canelo" Alvarez in a high-profile WBA title fight in Las Vegas on May 7, a bout that has faced calls for cancellation.
Ukraine's former world heavyweight champion Wladimir Klitschko, whose older brother Vitali is mayor of Kyiv, told the BBC this week that the fight should not be allowed to proceed.
Last month, heavyweight champion Oleksandr Usyk joined a territorial defense battalion in Ukraine as the nation seeks to defend itself against an invasion from Russia.
Usyk's longtime friend, Vasiliy Lomachenko, also joined a territorial defense battalion while Hall of Fame boxer Vitali Klitschko, the mayor of Ukraine's capital, Kyiv, announced he was taking up arms to defend against the invasion.
His brother, fellow Hall of Famer and former heavyweight champion Wladimir Klitschko, enlisted in Ukraine's reserve army in February in anticipation of the attack.