South Korea's spy agency says North Korea appears to have sent more troops to Russia, after its soldiers deployed on the Russian-Ukraine fronts suffered heavy casualties.

North Korea has deployed additional troops to Russia, but the scale of the contingent was not immediately known, South Korean media reported on Thursday, citing the country's intelligence agency. The additional troops have been sent to the battlegrounds in Russia's Kursk region,

Ukrainian troops holding positions in Kursk say the North Koreans have reappeared on the battlefield and become even more formidable foes.