Kim Jong Un has praised North Korean soldiers who killed themselves by detonating their grenades while fighting for Russia against Ukraine, confirming a long-suspected battlefield policy.

In a speech this week, the North Korean leader said those who "unhesitatingly opted for self-blasting, suicide attack, in order to defend the great honour" were "heroes".

South Korea estimates at least 15,000 North Koreans have been sent to help Russia recapture parts of western Kursk, and more than 6,000 have been killed so far. Neither Pyongyang nor Moscow have confirmed the numbers.

Intelligence agencies and defectors have said the soldiers were under Pyongyang's orders to kill themselves rather than be taken prisoner by Ukraine.

"Their self-sacrifice expecting no compensation, and the devotion expecting no reward... This [is] the definition of the height of loyalty of our army," Kim said in Pyongyang on Monday as he unveiled a memorial for fallen troops, state media KCNA reported.

Russian Defence Minister Andrey Belousov and the speaker of Russia's parliament, Vyacheslav Volodin, were among those who attended the event.

In North Korea, soldiers are taught that being captured is an act of treason.

Earlier this year, South Korean broadcaster MBC aired a programme featuring two North Korean prisoners of war in Ukraine, one of whom said on camera he regretted not taking his own life.

"Everyone else blew themselves up. I failed," the prisoner said.

Seoul's National Intelligence Service said last year they found memos on deceased North Korean soldiers that point to this extreme practice.

In his speech on Monday, Kim also praised those who died in combat.

"Those who fell in the vanguard of charges and those who writhed in frustration at the failure to fulfill their duties as soldiers who were given orders, rather than in pain in their bodies torn by bullets and shells – they too can be called the party's faithful warriors and patriots," Kim said.

In June 2024, Russian President Putin and Kim signed a deal pledging that their countries would help each other in the event of "aggression" against either country. At the time, Kim hailed the treaty as the "strongest ever".

Besides sending soldiers, North Korea also promised to send thousands of workers to help rebuild Kursk.