Ukrainian President Volodymyr Zelenskyy said on Wednesday that North Korea was a de facto participant on Russia's side in its war against Ukraine, Paralel.Az reports citing Reuters.

In a speech to parliament, the Ukrainian leader said his intelligence services had confirmed North Korea's supply to Russia of both weapons and people.

"Our intelligence records not only the transfer of weapons from North Korea to Russia, but also the transfer of people," Zelenskyy told the parliament.

"These are workers for Russian factories to replace Russians killed in the war. And personnel for the Russian army. In fact, this is the participation of a second state in the war against Ukraine on the side of Russia."

On Sunday, Zelenskyy accused North Korea of transferring personnel to Russia's armed forces but the Kremlin has dismissed the allegation as "fake news."

White House National Security Council spokesperson Sean Savett said on Tuesday the involvement of North Korean troops in Ukraine, if true, would mark a significant increase in the North Korea-Russia defence relationship.