Wagner boss Yevgeny Prigozhin was on the passenger list of a jet which crashed killing all on board, Russia's civil aviation authority has said.
Earlier, Wagner-linked Telegram channel Grey Zone reported the Embraer aircraft was shot down by air defences in the Tver region, north of Moscow.
The jet, which was flying from Moscow to St Petersburg, was carrying seven passengers and three crew.
Prigozhin led a failed mutiny against the Russian armed forces in June.
Grey Zone said local residents heard two bangs before the crash and saw two vapour trails.
Tass news agency said the plane caught fire on hitting the ground, adding that four bodies had already been found.
The aircraft had been in the air for less than half an hour, it said.
BBC