Russia's FSB security service accused Wagner Group leader Yevgeny Prigozhin of calling for an "armed rebellion" when he vowed retaliation after claiming Moscow's military killed a "huge amount" of his mercenaries in a strike on a camp.

The FSB urged Wagner fighters to "stop the columns" and detain their leader. Russian state TV interrupted programming Friday night to report a defense ministry statement claiming Prigozhin's comments did not correspond to reality.

Security has been stepped up around Moscow — whose mayor said "anti-terrorist measures" are being carried out — and in the city of Rostov near southeast Ukraine, state media reported.

Russia said Kyiv was "taking advantage" of Prigozhin's "provocation" to make inroads around the eastern city of Bakhmut.