North Korea has suffered some 4700 casualties so far, including injuries and deaths, though its troops have shown signs of improved combat capabilities over about six months by using modern weapons like drones, the lawmakers said.
In return for dispatching troops and supplying weapons to Russia, Pyongyang appears to have received technical assistance on spy satellites, as well as drones and anti-air missiles, they said.
"After six months of participation in the war, the North Korean military has become less inept, and its combat capability has significantly improved as it becomes accustomed to using new weapons such as drones," Lee Seong-kweun, a member of the parliamentary intelligence committee, told reporters, after being briefed by South Korea's National Intelligence Service.
Pyongyang earlier this week confirmed for the first time that it had sent troops to fight for Russia in the war in Ukraine under orders from leader Kim Jong-un and that it had helped regain control of Russian territory occupied by Ukraine.
North Korea's unprecedented deployment of thousands of troops, as well as massive amounts of artillery ammunition and missiles, gave Russia a crucial battlefield advantage in the western Kursk region and has brought the two economically and politically isolated countries closer.
Lee added that bodies of dead North Korean soldiers were cremated in Kursk before being shipped back home. Pyongyang is also believed to have sent about 15,000 workers to Russia, said the lawmakers, citing intelligence assessments.
North Korean labour overseas is known as a source of the regime's hard currency income but UN sanctions prohibit the use of North Korean labour in third countries.
Both Kim and Russian President Vladimir Putin said the North Korean deployment was made under their countries' landmark 2024 defence treaty, which requires each side to provide aid if the other is attacked.
with AP