The officials, who spoke on grounds of anonymity, said that out of the estimated 11,000 troops sent from North Korea, known as DPRK (Democratic People's Republic of Korea), 4,000 were battle casualties.

A thousand North Korean troops who have been fighting in the Kursk region of Russia have been killed in Vladimir Putin ’s war with Ukraine, officials have said. Western officials have told the BBC that 36 per cent of North Korean forces fighting in Russia had been killed, injured or captured by mid-January.

Videos of captured North Korean troops posted online by Ukrainian President Zelensky show them admitting that they thought they were being sent on an exercise.

According to Ukrainian President Volodymyr Zelensky, North Korean soldiers were transported to Russian territory by ferry, then by train, and kept in total isolation as far as information was concerned.

North Korean leader Kim Jong-un reportedly sent New Year’s messages to North Korean soldiers deployed in Russia's war against Ukraine, urging them to "fight with courage" until the end, according to a news report.