Wagner warlord Yevgeny Prigozhin has bragged about turning convicted killers into "real cannibals".
The mercenary group consists of around 50,000 prisoners, including rapists and murderers, who will be pardoned and free to live in society if they survive six months of war - regardless of how heinous their crimes are.
Prigozhin was seen in a video at a special training ground for his private paramilitary fighters in the Krasnodar region of southern Russia.
The Putin crony has boasted about making the hardened criminals even more dangerous before they are deployed to Ukraine to support the war effort.
In the video, Prigozhin - who has been nicknamed 'Putin's chef' because of his catering background - said: "This is a supplementary training base for our fighters.
"The primary training is in Molkino (Krasnodar region), and here experienced fighters are given additional training in their specialties.
"So they raise young eagles there [in Molkino]. And here they make real cannibals."
Prigozhin, who spent time in jail himself for assaulting and robbing a woman, mocked foes who criticise him for running a private army with appalling losses on the frontline.
He slammed those who "were once in the army" or "once wore the shoulder straps of a general" in the "distant past".
Prigozhin said: "Live in the present. [This is] a war unlike anything that has happened, in the previous century or this one - except World War II."