An injured North Korean soldier captured by Ukrainian forces has died, Yonhap News Agency has reported, citing a statement from South Korea’s spy agency.

The soldier is believed to be the first North Korean prisoner of war captured since Pyongyang deployed forces to support Russia’s war in Ukraine.

South Korea’s National Intelligence Service said it had confirmed through an “allied intelligence agency” that the soldier had died from “serious injuries”, Yonhap reported.

North Korea has sent more than 10,000 soldiers to help Russia, according to Kyiv and Seoul – though Moscow and Pyongyang have neither confirmed nor denied their presence.

The spy agency earlier confirmed that Ukrainian forces had captured the soldier after a photo purporting to show the man had been circulating on Telegram.

“This is the first in a string of captures and killings,” Yang Uk, a research fellow at the Asan Institute for Policy Studies, told the BBC. “For Ukrainians, it’s more beneficial to capture these North Korean troops and try to exchange them with Russians for Ukrainian prisoners of war.”

Recent images emerging from the Russia-Ukraine war confirmed speculations that “North Korean troops will be deployed in large numbers to the assault by Russian command”, Mr Yang said.

He also added, however, that “it will be challenging to prove their North Korean nationality”.

Ukrainian forces say that North Korean soldiers have been issued with fake Russian IDs, while Ukrainian President Volodymyr Zelensky posted footage last week which he said showed Russian troops burning the faces of slain North Koreans to conceal their identities.

Ukrainian and South Korean intelligence services have said that many of the troops deployed to Russia are some of Pyongyang’s best, drawn from the 11th Corps, also known as the Storm Corps. The unit is trained in infiltration, infrastructure sabotage and assassinations.

More than 3,000 North Korean troops have died or been wounded while fighting in Russia’s Kursk region, Zelensky said Monday.

He added that the collaboration between Moscow and Pyongyang heightened the “risk of destabilisation” around the Korean peninsula.

Russia launched a full-scale invasion of Ukraine in February 2022. The recent deployment of North Korean troops to Russia is a sign of a growing alliance between the two pariah states.

The development, which comes as North Korea ratchets up tensions with South Korea, has sparked worries in the West. China, a long-standing ally of both sides, is also keeping a cautious eye on the friendship.

Additional reporting by Jake Kwon