Russian investigators said on Sunday that genetic tests had confirmed that Yevgeny Prigozhin, chief of the Wagner mercenary group, was among the 10 people killed in a plane crash last week.

Russia's aviation agency had previously published the names of all 10 people on board the private jet which crashed in the Tver region northwest of Moscow on Wednesday. They included Prigozhin and Dmitry Utkin, his right-hand man who helped found the Wagner group.

"As part of the investigation of the plane crash in the Tver region, molecular-genetic examinations have been completed," Russia's Investigative Committee said in a statement on the Telegram messaging app.

"According to their results, the identities of all 10 dead were established. They correspond to the list stated in the flight sheet," it said.

There had been some speculation, especially on pro-Wagner Telegram channels, about whether Prigozhin - who was known to take various security precautions in anticipation of a possible attempt on his life - had really been on the doomed flight.

Authorities have yet to say what they believe caused his private jet to fall from the sky.

'STAB IN THE BACK'

The crash came two months to the day after Prigozhin and his Wagner mercenaries staged a mutiny against Russian military commanders in which they took control of a southern city, Rostov, and advanced towards Moscow before turning around 200 kilometres from the capital.

Russian President Vladimir Putin described the June 23-24 mutiny as a treacherous "stab in the back", but later met with Prigozhin in the Kremlin. He sent his condolences on Thursday to the families of those believed to have died in the crash.

Western politicians and commentators have suggested, without presenting evidence, that Putin ordered Prigozhin to be killed as punishment for the mutiny, which also represented the biggest challenge to Putin's own rule since he came to power in 1999.

Kremlin spokesman Dmitry Peskov said on Friday that such suggestions were "an absolute lie". Asked whether Putin might attend Prigozhin's funeral, Peskov said it was too early to say and also noted the president's "busy schedule".

Wagner fighters played a prominent role in the fighting in eastern Ukraine, especially in the months-long siege of the city of Bakhmut, despite Prigozhin's frequent, profanity-laced attacks on Russia's military high command over their conduct of the war that culminated in the failed mutiny.

The Wagner fighters have now left Ukraine and some have relocated to neighbouring Belarus under the terms of a deal that ended their mutiny.

Some are expected to be absorbed into Russia's armed forces but many will be angry over the sudden demise of the group's founder who inspired a high degree of loyalty among his men.

Putin paid a mixed tribute to Prigozhin on Thursday, describing him as a "talented businessman" but also as a flawed character who "made serious mistakes in life".