Seoul has warned Ukraine it will consider unspecified further action if the Ukrainian president fails to issue a public apology over the recent UN disclosure that two North Korean prisoners of war were transferred to South Korea.

The revelation was made at a UN General Assembly session last week by Ukraine's president Volodymyr Zelensky and has provoked a sharp response from Seoul, which had insisted the matter remain confidential.

Ukraine's foreign minister Andrii Sybiha dismissed the incident as a diplomatic misunderstanding and said Kyiv was working to resolve the issue.

However, President Lee Jae Myung slammed the gesture on the social platform X, characterising it as a threat that could bring war to the Korean Peninsula and accusing Kyiv of attempting to provoke conflict.

Seoul has long offered support to Ukraine in the face of Russia's invasion but maintains a policy of not providing lethal weapons to any party in an active conflict, emphasising it cannot tolerate actions it perceives as undermining the dignity of the Korean people.

The two North Korean soldiers, recruited to fight in Ukraine, had earlier expressed a desire to be transferred to the South and have now been repatriated.

Lee has faced domestic criticism for the appearance of covering up the transfer to appease Pyongyang, while opposition figures argue he should have kept the move secret from Kyiv.

Kyiv insists no agreement existed to keep the transfer confidential, while Seoul reiterates that the move was requested to protect families and avoid criticism that the soldiers could be exchanged for Ukrainian prisoners of war.

The incident underscores the delicate balance Seoul must maintain between supporting Ukraine and managing its relationship with North Korea, while also navigating the broader tensions on the Korean Peninsula.