Russian President Vladimir Putin has said hand grenade fragments were found in the bodies of people who died when mercenary chief Yevgeny Prigozhin’s plane crashed on August 23.
Experts investigating the crash found no indication the private jet had suffered an “external impact”, he added.
Mr Prigozhin and two of his top lieutenants in the Wagner private military contractor were among the 10 people killed when the jet came down as it flew from Moscow to St Petersburg.
There was no way to independently verify Mr Putin’s statement.
The Kremlin described the allegation he was behind the crash as an “absolute lie”.
A Russian investigation was launched but no findings have been released. Moscow rejected an offer from Brazil, where the Embraer business jet was built, to join the inquiry.
Mr Putin said the investigation is continuing and stopped short of saying what caused the crash, but his statement appeared to hint the plane was brought down by a grenade explosion.
Mr Prigozhin’s aborted rebellion in June marked the most serious challenge to the president, who has been in power for more than two decades. The crash came two months to the day after the rebellion started.
Mr Putin also noted that while investigators have not tested the remains for alcohol and drugs, 11lb of cocaine was found during searches at Mr Prigozhin’s office in St Petersburg after the mutiny — an apparent attempt to denigrate the mercenary chief.
After his death, the president described Mr Prigozhin, 62, as “a man of difficult fate” who had “made serious mistakes in life”.
The Wagner Group military contractor that he created has been active in Ukraine, Syria and several African countries and counted tens of thousands of troops at its peak.
It played a key role in the fighting in Ukraine, where it spearheaded the capture of the eastern Ukrainian city of Bakhmut in May after months of bloody combat.
In the June 23-24 rebellion, Mr Prigozhin said it was intended to oust the Defence Ministry’s leadership who he blamed for mistakes in pressing the fighting in Ukraine.
His mercenaries took over Russia’s southern military headquarters in Rostov-on-Don and then rolled towards Moscow before abruptly halting the mutiny under a deal that offered them amnesty from prosecution.
The mercenaries were given a choice to retire from the service, move to Belarus or sign new contracts with the Defence Ministry.
Last week, Mr Putin met one of Wagner’s top commanders to take charge of “volunteer units” fighting in Ukraine, in a sign that the Kremlin intends to keep using the mercenaries after Mr Prigozhin’s death.
The president said on Thursday that several thousand Wagner troops have signed contracts with the Defence Ministry.