Ukrainian President Volodymyr Zelenskyy said Sunday he was ready to hand over captured North Korean soldiers to Pyongyang in exchange for the return of Ukrainian POWs held in Russia.

Zelenskyy's offer came hours after South Korea's National Intelligence Service confirmed Ukraine's announcement from the previous day that it had captured two North Korean soldiers.

Kyiv said Saturday they had been wounded fighting Ukraine's troops in Russia's Kursk region, but at the time did not provide any proof of their nationality.

But on Sunday, the NIS told AFP it had "confirmed that the Ukrainian military captured two North Korean soldiers on January 9 in the Kursk battlefield in Russia".

In a post on X Sunday, Zelenskyy said: "Ukraine is ready to hand over Kim Jong Un's soldiers to him if he can organize their exchange for our warriors who are being held captive in Russia."

There would "undoubtedly be more" North Korean soldiers captured by Kyiv, he added.

"For those North Korean soldiers who do not wish to return, there may be other options available," said Zelenskyy.

"In particular, those who express a desire to bring peace closer by spreading the truth about this war in Korean will be given that opportunity."

Ukraine, the United States and South Korea have accused nuclear-armed North Korea of sending more than 10,000 soldiers to help bolster Russian forces.

Neither Moscow nor Pyongyang has acknowledged that North Koreans have been deployed to fight against Ukraine.

The two countries have boosted their military cooperation since Russia launched its 2022 invasion of Ukraine.

"There should be no doubt left in the world that the Russian army is dependent on military assistance from North Korea," said Zelenskyy.

The Ukrainian president posted a video of an interrogation of the two North Korean prisoners of war, one of whom is lying in a bunk bed and the other is sitting up in bed with a bandage around his jaw.

One man can be heard speaking to a Ukrainian official through an interpreter, saying in translated comments that he did not know he was going to fight in a war with Ukraine and that his commanders "told him it was just training".

In translated comments, one of the men says he wants to return to North Korea. The other says he will do what he is told but, if given the chance, wants to live in Ukraine.

South Korea's confirmation Sunday added weight to Kyiv's account, confirming details released by Ukraine the previous day.

The NIS said one of the captured soldiers had revealed that he received military training from Russian forces after arriving there in November.

"He initially believed he was being sent for training, realizing upon arrival in Russia that he had been deployed," the NIS said.

The soldier also said North Korean forces had experienced "significant losses during battle".

The NIS said it would continue to work with the SBU to share information on North Korean fighters in Ukraine.

Neither Russia nor North Korea has reacted to the intelligence accounts.

Zelenskyy said last month that nearly 3,000 North Korean soldiers had been "killed or wounded" fighting for Russia. Seoul put the figure at 1,000.

The NIS told the country's lawmakers last month that "several North Korean casualties" had already been attributed to Ukrainian missile and drone attacks as well as training accidents, with the highest ranking "at least at the level of a general".

Due to losses among its forces, North Korea is preparing for additional deployment to Ukraine, according to Seoul's military.

Russia on Sunday claimed the capture of two villages in eastern Ukraine where its forces have been advancing for months.

The defense ministry said forces had captured the village of Yantarne in the eastern Donetsk region, around 10 kilometers (six miles) southwest of Kurakhove, a key logistics hub that Moscow claimed to have seized last week.

Russian troops also captured the village of Kalinove in the northeastern Kharkiv region, said the ministry.