Russia's security authority has begun a criminal investigation into Yevgeny Prigozhin, the leader of the private military firm Wagner Group who has been at odds with the country's defense ministry.

Russia's prosecutor general announced on Friday that the Federal Security Service, or FSB, initiated the investigation, suspecting Prigozhin of calling for an armed rebellion.

Prigozhin said in a social media post on Friday that his forces were attacked by the Russian military. He vowed to stop what he calls the evil of the military leadership.

The defense ministry immediately issued a statement on social media, branding his claim an "information provocation".

State television interrupted a regular program with a news report on the investigation of Prigozhin, along with the defense ministry's statement.

Russian presidential spokesperson Dmitry Peskov said that President Vladimir Putin has been informed of the situation and that necessary measures were being taken.

The Wagner Group has been fighting in Ukraine, alongside Russian forces.

Prigozhin accused the Russian defense minister of falsely reporting the situation on the battlefields.

He said in a video post on Friday that the defense minister Sergei Shoigu and other military leaders are trying to deceive society and the president.

He claimed that the Ukrainian forces are pushing the Russians back in the south, as they have begun their counteroffensive.

He said that the Russians are bathing in their own blood.

In his post on Friday, Prigozhin even contradicted the Kremlin's justification of invading Ukraine. Russia had claimed that it was necessary in the face of the persecution of Russian residents in the eastern part of Ukraine and the military threats from NATO.

He said that what is called the "special military operation" was initiated with completely different reasons.