The head of Russia's Wagner mercenary group is being investigated for inciting mutiny after accusing the Russian military of a launching a deadly missile strike on his troops.
Yevgeny Prigozhin said the "evil" in the military leadership must be stopped and vowed to "march for justice".
Authorities have denied the strike and demanded he halt "illegal actions".
President Putin was aware of the situation and all necessary measures were being taken, his spokesman said.
It represents an astonishing escalation of infighting inside Russia.
The Wagner Group is a paramilitary organisation that has been fighting alongside Russian forces in Ukraine. In recent months, Prigozhin has become increasingly vocal in his criticism of Russia's military leadership.
In an audio message posted to the social media platform Telegram, he said "the evil which the Russian military leadership carries must be stopped".
"Those who killed our lads, and tens of thousands of lives of Russian soldiers [in the war in Ukraine] will be punished," he said.
"I ask you not to resist. Anyone who does will be considered a threat and destroyed. That goes for any checkpoints and aviation on our way.
"Presidential power, the government, the police and Russian guard will work as usual.
"This is not a military coup, but a march of justice. Our actions do not interfere with the troops in any way."
Russian state media reports that the FSB, Russia's security services, have opened a criminal case against Prigozhin, accusing him of "calling for an armed rebellion". The Kremlin has also said "necessary measures are being taken", according to Russian news agency Interfax.
The Russian defence ministry said in a statement that "all reports by Prigozhin spread on social media" of Russian strikes on Wagner camps were "not true and are an information provocation".
It comes after a video message in May in which Prigozhin stood surrounded by the bodies of his troops and berated Mr Shoigu - as well as Chief of the General Staff Valery Gerasimov - for not providing them with enough ammunition.
Earlier on Friday, he said the war in Ukraine had been started "so that Shoigu could become a Marshal".
"The Ministry of Defence is trying to deceive the public, deceive the president and tell a story that there was some crazy aggression by Ukraine, that - together with the whole Nato bloc - Ukraine was planning to attack us," he said.
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from Via PakapNews