At least 18 soldiers provided to Putin by Kim Jong Un were said to have abandoned their positions after arriving to the front, Ukrainian media reports.
Some 18 North Korean soldiers are believed to have deserted the Russian frontline, with Kremlin fighters reportedly searching for them.
The troops were deployed in Russia's Kursk and Bryansk oblasts, about four miles from the border with Ukraine, when they deserted, the public broadcasting company of Ukraine, Suspilne, reported.
Intelligence officials cited by the broadcaster said the Russian military is searching for the North Korean soldiers, while commanders are trying to conceal the desertion from their higher-ups.