The chief of the Russian paramilitary group Wagner, Yevgeny Prigozhin, on Saturday asked Moscow to let him hand over his positions in the flashpoint Ukraine city of Bakhmut to Chechen leader Ramzan Kadyrov.

Wagner fighters are leading the battle for Bakhmut, during which rivalries between Prigozhin and the Russian army have come to the surface.

Wagner has spearheaded the grinding, months-long Russian assault on Bakhmut, almost capturing the city in the longest and bloodiest battle of the Russian campaign in Ukraine.

"I ask you to issue a combat order before 00:00 on May 10 concerning the transfer of the positions of the Wagner paramilitary units in Bakhmut and its periphery, to the units of the Akhmat battalion" Prigozhin said in a letter to Defence Minister Sergei Shoigu.

The Akhmat battalion refers to combat units under the command of strongman Kadyrov, who has ruled Russia's Muslim-majority republic Chechnya for the last decade-and-a-half.

In a series of scathing videos on Friday, Prigozhin blamed Shoigu and Chief of General Staff Valery Gerasimov for "tens of thousands" of killed and wounded Russian fighters in Ukraine.

"Their unprofessionalism is destroying tens of thousands of Russian guys and that is unforgivable," he had said.

Prigozhin said his fighters would be forced to pull out because of an "ammunition famine," adding that the Russian defence ministry had only delivered 32 percent of the required ammunition since October.

Kadyrov later said on Telegram his forces were "ready to move" towards Bakhmut.

"The soldiers are on alert, we are just waiting for orders," he said. (AFP)