Wagner mercenary chief Yevgeny Prigozhin is listed as a passenger on a private jet which has crashed north of Moscow with no survivors, raising fears among his allies that he has been killed.
There was no immediate official confirmation that Prigozhin, Russia's most powerful mercenary and a self-declared enemy of the Russian Defence Ministry, was physically on board the plane which crashed early on Wednesday evening.
Reuters could not confirm that he was on the aircraft though a Telegram channel linked to Wagner pronounced him dead.
The channel, Grey Zone, declared Prigozhin a hero and a patriot who it said had died at the hands of unidentified people it called "traitors to Russia".
If confirmed, his death would leave the Wagner Group, which incurred President Vladimir Putin's wrath in June by staging an abortive armed mutiny against the army's top brass, leaderless and raise questions about its future operations in Africa and elsewhere.
Whoever or whatever was behind the crash, his death would also rid Putin of someone who had mounted the most serious challenge to the Russian leader's authority since he came to power in 1999.
There was no immediate comment from the Kremlin or the Defence Ministry.
"An investigation has been launched into an Embraer plane crash that occurred tonight in the Tver region," Rosaviatsia, Russia's aviation agency, was cited as saying by the state TASS news agency.
"According to the passenger list, the name and surname of Yevgeny Prigozhin is among them."
Russia's emergency situations ministry said in a statement that the aircraft, which had been travelling from Moscow to St. Petersburg, had crashed near the village of Kuzhenkino in the Tver Region.
It said that 10 people had been on board, including three crew members. According to preliminary information, everyone on board had been killed, it said.
US President Joe Biden said he was not surprised by reports that Prigozhin may have died in a plane crash, adding that not much happens in the country that Putin is not behind.
Soon after the plane dropped out of the sky, a second private jet linked to Prigozhin which also appeared to be heading to St Petersburg, Prigozhin's home base, turned back to Moscow, flight tracking data showed, and later landed.
Prigozhin, 62, spearheaded the mutiny against Russia's top army brass in late June which Putin said could have tipped Russia into civil war. Wagner fighters shot down Russian attack helicopters during the revolt, killing an unconfirmed number of pilots in a move which infuriated the military.
He also spent months criticising the way Russia was prosecuting its war in Ukraine, something Moscow calls a "special military operation", and had tried to topple Defence Minister Sergei Shoigu and Valery Gerasimov, the Chief of the General Staff.
Many Russians had wondered how he was able to get away with such brazen criticism.
The mutiny was ended by negotiations and an apparent Kremlin deal which saw Prigozhin agree to relocate to neighbouring Belarus. But in practice he had appeared to move freely inside Russia after the deal.
He posted a video address on Monday which he suggested was taken in Africa and turned up at a Russia-Africa summit in St Petersburg in July.
Unconfirmed Russian media reports said Dmitry Utkin, Prigozhin's right-hand man, had also been on board and that Prigozhin and his associates had attended a meeting with officials from the Russian Defence Ministry.
Reuters could not confirm that and there was no confirmation from the defence ministry.
Flightradar24 online tracker showed that the Embraer Legacy 600 (plane number RA-02795) said to be carrying Prigozhin had dropped off the radar at 6.11 pm. An unverified video clip posted to social media showed a plane resembling a private jet falling out of the sky toward the earth.
Another unverified clip showed the still burning wreckage of the plane on the ground. At least one body was visible. Rescuers had recovered seven bodies from the scene, TASS reported.
