Ukrainian President Volodymyr Zelenskyy has said North Korean soldiers deployed to western Russia have been killed or injured during combat against Ukrainian forces, adding to global criticism they will be used as "cannon fodder" for Moscow, a Japanese report showed.

Zelenskyy shared the assessment during an interview with Japan's Kyodo news agency on Sunday without providing further details on the number of casualties, saying Kyiv needs "to have proof" before disclosing the figures.

He said the deployment of North Korean troops to the frontlines of combat will likely equip them with modern warfare experience, involving drones and recent technologies, which could have a "tremendous" impact on Asia should they return home.

The assessment came after North Korean leader Kim Jong-un met Russia's defense minister in Pyongyang last week and expressed his support for Russia's war against Ukraine, amid growing concerns over the protracted war further expanding.

North Korea has not publicly confirmed its troop deployment to Russia. But South Korea and the United States have said some of the North's deployed soldiers have already entered combat in Russia's western Kursk region.

Zelenskyy, meanwhile, reiterated the need for his country to join the North Atlantic Treaty Organization, noting that support from its partners is "not enough" and that the war with Russia has shifted to a "complicated period" with Moscow advancing faster in eastern Ukraine, according to the report. (Yonhap)