A North Korean soldier who was captured while fighting in Russia's war against Ukraine has died of his wounds, South Korea's spy agency said on Friday.
Pyongyang has deployed thousands of troops to reinforce Russia's military, including in the Kursk border region where Ukraine mounted a shock border incursion in August.
One of those North Korean soldiers was captured alive by the Ukrainian army on Thursday, a South Korean intelligence source told AFP, adding that the location where he was seized was not known.
Hours later, Seoul's National Intelligence Service (NIS) said that the soldier had succumbed to his wounds.
"It has been confirmed through an allied intelligence agency that the North Korean soldier captured alive on December 26th has just passed away due to worsening wounds," the South's spy agency said in a statement.
Friday's confirmation came days after Ukrainian President Volodymyr Zelensky said that nearly 3,000 North Korean soldiers had been "killed or wounded" so far as they joined Russian troops in combat.
South Korea's intelligence service had previously put the number of killed or wounded North Koreans at 1,000, saying the high casualty rate could be down to an unfamiliar battlefield environment and their lack of capability to counter drone attacks.
Pyongyang's soldiers were also being "utilized as expendable frontline assault units", lawmaker Lee Seong-kweun said, speaking last week after a briefing by South Korea's spy agency.
- 'Dangerous expansion' -
North Korea and Russia have strengthened their military ties since Moscow's invasion of Ukraine in February 2022.
A landmark defense pact between Pyongyang and Moscow signed in June came into force this month, with Russian President Vladimir Putin hailing it as a "breakthrough document".
North Korean state media said Friday that Putin sent a New Year's message to North Korean leader Kim Jong Un, saying "the bilateral ties between our two countries have been elevated after our talks in June in Pyongyang".
Ukraine's allies have called Pyongyang's growing involvement in Russia's war in Ukraine a "dangerous expansion" of the conflict.
Seoul's military believes that North Korea was seeking to modernize its conventional warfare capabilities through combat experience gained in the Russia-Ukraine war.
NATO chief Mark Rutte had also said that Moscow was providing support to Pyongyang's missile and nuclear programs in exchange for the troops.
South Korea's Joint Chiefs of Staff (JCS) said Monday that Pyongyang is reportedly "preparing for the rotation or additional deployment of soldiers" and supplying "240mm rocket launchers and 170mm self-propelled artillery" to the Russian army.
Pyongyang's involvement in Russia's war against Ukraine had prompted warnings from Seoul.
South Korea's President Yoon Suk Yeol, currently suspended, said in November that Seoul was "not ruling out the possibility of providing weapons" to Ukraine, which would mark a major shift to a long-standing policy barring the sale of weapons to countries in active conflict.