"In my personal opinion, more drastic measures should be taken, up to the declaration of martial law in the border areas and use of low-yield nuclear weapons," Kadyrov said on his Telegram channel.

He said that there is "no place for nepotism in the army" and called Colonel-General Alexander Lapin, who is in charge of Russia's forces fighting in the region, "mediocre".

He said Lapin did not provide the "necessary communication, interaction and supply of ammunition" to pro-Russian troops in Lyman, a town in the eastern Donetsk region that Moscow annexed a day earlier.

Moscow said it was withdrawing troops from Lyman on Saturday after capturing the town in late spring.

"I would have demoted Lapin to the rank of private, deprived him of his awards and, with a machine gun in his hands, sent him to the front lines to wash away his shame in blood," Kadyrov told his 2.8 million followers on Telegram.

Kadyrov is in charge of Russia's Muslim-majority Chechnya Republic which he governs with an iron fist.