North Korea has sent more soldiers to Russia and redeployed several to the front line in Kursk, Seoul's spy agency said on Thursday.

South Korean and Western intelligence agencies have said that more than 10,000 soldiers from the reclusive state were sent to Russia last year to help it fight a shock Ukrainian offensive into the Kursk border region.

Seoul said earlier this month North Korean soldiers previously fighting alongside Russia's army on the Kursk front line had not been engaged in combat since mid-January.