North Korean troops fighting for Russia have been pulled from the front line for extra training after crude tactics led to massive casualties.

North Korean troops have not been seen on the frontlines in Russia’s Kursk region for several weeks, a Ukrainian military official said Friday, amid reports of mass casualties among Pyongyang’s forces.

North Korean troops are no longer fighting on Russia’s behalf in Vladimir Putin’s war against Ukraine, according to reports. Pyongyang signed a mutual defence agreement with Moscow last year, promising to defend one another if a third party were to attack.

North Korea sent its best troops to aid Russia in its war against Ukraine. But after months of suffering severe losses, they have been taken off the front line.

The soldiers appear to have been pulled back from the front lines in Kursk after suffering heavy casualties during barely a month of combat, Ukrainian officials said.

Ukranian reports indicate that the North Korean soldiers previously encountered have withdrawn from the frontline. This report is limited to the Kursk region, where a large part of the recent fighting has been going on.

Ukrainian special forces tell the BBC they have not seen any North Koreans in Russia's Kursk region in three weeks.