Russian President Vladimir Putin says his country is facing a "betrayal" and has instructed the military to take decisive action.

Putin delivered an emergency speech Saturday on state-run TV.

His remarks come after Russia's Federal Security Service launched a criminal investigation into allegations that the leader of the private military firm Wagner Group, Yevgeny Prigozhin, had called for an armed rebellion.

Putin said excessive ambition and egoism have led to treason, and described any rebellion as a "fatal threat" to the Russian state. He said tough action will be taken to protect the homeland from such threats.

In an apparent reference to the Wagner forces, Putin said he strongly urges "those who are being dragged into this crime to make the only right choice without making a fatal and tragic mistake." He warned they must not participate in criminal acts.

Prigozhin has been increasingly at odds with Russia's defense ministry over operations in Ukraine. He said on social media on Friday that the Russian military had attacked his forces.

After Putin's speech, the governor of the western Russian region of Voronezh said on social media that Russian troops were taking "necessary military measures" there as part of a counter-terrorist operation.

The remarks suggest fighting had broken out in Voronezh between Russian troops and Wagner fighters.
Voronezh is adjacent to the southern region of Rostov. Prigozhin claimed earlier on Saturday that his forces had taken control of Rostov's Russian military facilities.