Yevgeny Prigozhin
Yevgeny PrigozhinReuters

Wagner mercenary group leader Yevgeny Prigozhin was buried quietly in a cemetery on the outskirts of St Petersburg on Tuesday, six days after he was killed in an unexplained plane crash, Reuters reported.

The funeral took place away from the glare of the media and in stark contrast to the brazen, self-publicizing style with which Prigozhin had fanned his reputation, in Russia and far beyond, for ruthlessness and ambition.

"The farewell to Yevgeny Viktorovich took place in a closed format. Those who wish to say goodbye may visit Porokhovskoye cemetery," his press service said in a short post on Telegram.

Prigozhin, two top lieutenants of his Wagner group and four bodyguards were among 10 people who died when his Embraer Legacy 600 private jet crashed north of Moscow on August 23.

The crash came exactly two months after Prigozhin led a failed mutiny against Russian army chiefs.

Authorities have yet to say what they believe caused his private jet to fall from the sky. US and Western officials said last week that a preliminary US intelligence assessment concluded that an intentional explosion caused the crash.

Russian President Vladimir Putin last week denied having any connection to Prigozhin’s death, as he sent his condolences to the families of those killed in the crash.

Meanwhile on Tuesday, White House press secretary Karine Jean-Pierre gave her strongest statement yet about the possibility that Putin directed the killing of Prigozhin.

"We all know that the Kremlin has a long history of killing opponents," she said. "It's very clear what happened here."

The Kremlin has rejected as an "absolute lie" the suggestion that Putin ordered Prigozhin’s death in revenge for the June mutiny. It said earlier on Tuesday that the president would not attend the funeral.

Last Friday, the Russian President ordered Wagner Group fighters to sign an oath of allegiance to the Russian state.

The decree, published on the Kremlin website, obliges anyone carrying out work on behalf of the military or supporting what Moscow calls its "special military operation" in Ukraine to swear a formal oath of allegiance to Russia.