Social media linked to the Wagner mercenary group say his private plane was shot down by Russian air defences. Prigozhin died "as a result of actions of traitors to Russia", the Grey Zone Telegram channel posted.
Prigozhin led an aborted mutiny against Russia's armed forces in June. However, some experts in Russia and abroad suggest the revolt was staged, and Prigozhin abandoned his "justice march" on Moscow after direct orders from President Vladimir Putin.
Wednesday's crash in the Tver region, north-west of the capital Moscow, comes on the same day that senior Russian general Sergei Surovikin was reportedly sacked as air force chief.
Gen Surovikin was known to have good relations with Prigozhin and had not been seen in public since the mutiny. Prigozhin's aircraft - an Embraer-135 (EBM-135BJ) - was flying from Moscow to St Petersburg on Wednesday with seven passengers and three crew, Russia's Rosaviatsia aviation authority said.
Senior Wagner commander Dmitry Utkin - who founded the group in 2014 - was also on the passenger list, it said. The plane is reported to have come down near the village of Kuzhenkino, about half-way between Moscow and St Petersburg.
One report said the body of Prigozhin, 62, had been found and identified - this has not been officially confirmed. All 10 bodies have been recovered, Russia's state-run news agency Interfax said.
Grey Zone said local residents had heard two bangs before the crash and had seen two vapour trails. Tass news agency said the plane had caught fire on hitting the ground. The aircraft had been in the air for less than half-an-hour, it added. An investigation has been launched into the crash and emergency services are searching the scene.
At the same time, Grey Zone reported that a second business jet owned by Prigozhin had landed safely in the Moscow region.
(BBC)