North Korean leader Kim Jong Un lauded "heroic" North Korean troops who fought for Russia in the war against Ukraine, in a ceremony decorating soldiers of the army's overseas operation, state media KCNA said on Friday.

Kim said in a speech, "The combat activities of overseas operational forces... proved without regret the power of the heroic (North Korean) army," and said the "liberation of Kursk" proved the "fighting spirit of the heroes".

Kim laid a flower at a memorial wall for soldiers fallen overseas, and a concert was held for soldiers returned from Russia as well as a banquet that included bereaved family members, KCNA added.

The moves were the latest public honouring of North Korean troops who fought in Russia. KCNA said on Thursday that Kim met with officers of the army's overseas operation and paid tribute to North Korean soldiers killed in Ukraine.

About 600 North Korean troops have been killed fighting for Russia against Ukraine out of a total deployment of 15,000, South Korean lawmakers said in April, citing the country's intelligence agency. (Reuters)