Russia has hit Ukraine with missiles supplied by North Korea, Ukrainian presidential aide Mykhailo Podolyak said on Friday following an earlier assertion by Washington.

"There is no longer any disguise ... as part of its outright genocidal war, the Russian Federation for the first time struck at the territory of Ukraine with missiles received from ... North Korea," Podolyak wrote on X social media.

Earlier on Friday, state media quoted the governor of the eastern Ukrainian region of Kharkiv as saying missiles produced outside Russia had been fired into the province at the end of December and beginning of January.

"[Russia] is attacking Ukrainians with missiles received from a state where citizens are tortured in concentration camps for having an unregistered radio, talking to a tourist, watching TV shows," Podolyak said.

Podolyak did not provide evidence for the missiles being North Korean. In its statement on Thursday, Washington cited declassified intelligence.