Around 300 North Korean soldiers have been killed and 2,700 wounded while fighting for Russia, a South Korean lawmaker said Monday, citing information from Seoul's spy agency.

Seoul has previously claimed that North Korean leader Kim Jong-un sent more than 10,000 soldiers to fight in the Ukraine conflict, in return for Russian technical assistance for Pyongyang's heavily sanctioned weapons and satellite programmes.

Over the weekend, Ukrainian President Volodymyr Zelensky said Kyiv had captured two North Korean soldiers, releasing video of the injured combatants being interrogated and raising the possibility of a prisoner swap for captured Ukrainian troops.

"The deployment of North Korean troops to Russia has reportedly expanded to include the Kursk region, with estimates suggesting that casualties among North Korean forces have surpassed 3,000," lawmaker Lee Seong-kweun told reporters after a briefing from the spy agency.

This includes "approximately 300 deaths and 2,700 injuries," Lee said, after a briefing from Seoul's National Intelligence Service (NIS).

The soldiers, reportedly from North Korea's elite Storm Corps, have been ordered to kill themselves rather than be taken prisoner, Lee said.

"Notably, memos found on deceased soldiers indicate that the North Korean authorities pressured them to commit suicide or self-detonate before capture," he said.

He added that some of the soldiers had been granted "amnesty" or wanted to join North Korea's ruling Workers' Party, hoping to improve their lot by fighting.

The NIS analysis also revealed that the North Korean soldiers have "a lack of understanding of modern warfare," and are being used by Russia in a manner leading to "the high number of casualties," the lawmaker said.

Lee -- speaking for South Korea's intelligence committee in parliament -- said in the coming year, US president-elect Donald Trump, who has previously tried to woo North Korean leader Kim Jong-un, "may push for dialogue... once again".

He also said Kim may "weigh the possibility of a visit to Russia in the first half of this year" after meeting Russian President Vladimir Putin in late 2023.

In a post on the social media platform X on Sunday, Zelensky said: "Ukraine is ready to hand over Kim Jong-un's soldiers to him if he can organise 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 Zelensky.

Neither Moscow nor Pyongyang has acknowledged that North Koreans have been deployed to fight. (AFP)