Wagner leader accuses the Russian military of attacking his mercenaries.

“The evil carried by the country’s military leadership must be stopped,” Mr. Prigozhin said.

The mercenary leader’s claims could not be immediately verified. The Russian defense ministry denied the allegations, saying in a statement that the messages Mr. Prigozhin had posted about supposed strikes on Wagner camps “do not correspond to reality.”

Mr. Prigozhin’s accusations created a ripple effect among Russian pro-war activists, who fear that an open conflict between the army and Wagner forces could threaten the Russian front lines during the Ukrainian counteroffensive. In Ukraine, some viewed his statements as more evidence of internal divisions within the Russian war effort.

In an earlier videotaped speech, Mr. Prigozhin did not explicitly impugn President Vladimir V. Putin, instead casting him as a leader being misled by his officials. But in dismissing the Kremlin’s narrative that the invasion was an existential necessity for the Russian nation, Mr. Prigozhin went farther than anyone in Russia’s security establishment in publicly challenging the wisdom of the war.

“The war wasn’t needed to return Russian citizens to our bosom, nor to demilitarize or denazify Ukraine,” Mr. Prigozhin said, referring to Mr. Putin’s initial justifications for the war. “The war was needed so that a bunch of animals could simply exult in glory.”

Friday’s diatribes deepened the enigma of Mr. Prigozhin’s ambiguous role in Mr. Putin’s system. His Wagner troops, composed of veteran fighters as well as thousands of convicts whom Mr. Prigozhin personally recruited from Russian prisons, proved key in capturing the Ukrainian city of Bakhmut in May after a monthslong battle.

But, during the battle for Bakhmut, Mr. Prigozhin also emerged as a populist political figure, excoriating Russia’s military leadership for corruption and for not providing his forces with enough ammunition. His angry recordings and videos posted to the Telegram messaging network cast top military and Kremlin officials as unaware and uncaring of the struggles of regular Russian soldiers.

Mr. Putin has not reined in Mr. Prigozhin, even as his security forces have jailed or fined thousands of Russians for criticizing the military or opposing the war. Some people who know Mr. Putin have said they believe that the president still sees Mr. Prigozhin as a loyal servant applying needed pressure on a sprawling military apparatus. Others theorize that the Kremlin has orchestrated Mr. Prigozhin’s tirades against Mr. Shoigu, the defense minister, to deflect blame from Mr. Putin himself.

But Friday’s video complicated the picture, with Mr. Prigozhin going after not just Mr. Shoigu but also unnamed “oligarchs” around Mr. Putin, while casting the entire official rhetoric around the invasion as a sham. He said there was “nothing out of the ordinary” in Ukraine’s military posture on the eve of the February 2022 invasion — challenging the Kremlin’s justification that Ukraine was on the verge of attacking Russian-backed separatist territory in Ukraine’s east.

“Our holy war with those who offend the Russian people, with those who are trying to humiliate them, has turned into a racket,” he said.

The comments come as Russia fights to hold back Ukraine’s counteroffensive — a fight that Mr. Prigozhin asserted in his video was going much more poorly for Russia than the government was letting on. On Telegram, pro-war commentators quickly pushed back against that assertion, including Igor Girkin, a former paramilitary commander who himself has often criticized Russia’s top brass.

“Prigozhin already should have been handed over to a military tribunal for many things,” Mr. Girkin wrote. “Now also for treason.”