Without detailing what specific measures would be taken, Seoul's foreign ministry said the restrictions would be similar to those previously imposed on Russia.

South Korea last month said it would tighten export controls against Moscow by banning shipments of strategic items and join Western countries in suspending financial transactions with several major Russian banks.

"Our government decided today to implement export control measures against Belarus as well, judging that Belarus is effectively supporting the Russian invasion of Ukraine," the ministry said in a statement.

Russia's military has used Belarus as an important staging ground for its assault on neighbouring Ukraine, though Belarusian strongman leader Alexander Lukashenko has stressed his own forces have not taken part.

South Korea's decision comes as Western governments, sporting organisations and a growing list of major companies have isolated Russia, levelling punishing sanctions over the internationally condemned attack on its neighbor.

After days of violence, Russian President Vladimir Putin on Saturday warned Ukraine it may cease to exist as a state if leaders "continue to do what they are doing".

He also said that any countries imposing a "no-fly zone" over Ukraine will be considered combatants while equating economic sanctions with a declaration of war.

The International Monetary Fund warned the already "serious" global economic impacts of the war in Ukraine would be "all the more devastating" should the conflict escalate.