Yevgeny Prigozhin, whose influence has risen hugely in Moscow's Ukraine offensive, has in recent days released a series of scathing videos attacking Russia's military leadership.
"Today one of the units of the defence ministry fled from one of our flanks... exposing the front," Prigozhin said in a video. He has threatened to pull his fighters out of Bakhmut on May 10 if he did not receive badly needed ammunition.
The mercenary group has spearheaded Moscow's fight for the east Ukrainian city.
Yevgeny Prigozhin, who has been increasingly unhinged with his criticism of Russia’s military leadership, on Tuesday blasted Russian generals for fighting a war "on television" and leaving his fighters hanging with no ammunition.
Mr Prigozhin’s press office put out his video statement just as President Putin wrapped up the annual Victory Parade on Red Square and claimed that Russian troops were successful in "carrying out their tasks" in Ukraine.
Mr Prigozhin last week offered the Kremlin a de-facto ultimatum, threatening to pull out thousands of his troops fighting outside Bakhmut by Wednesday unless the Russian defence ministry increases their supplies.