The Kremlin today rejected allegations it was behind a plane crash that is presumed to have killed mercenary leader Yevgeny Prigozhin, who conducted a brief but shocking mutiny in Russia two months ago.

Prigozhin, whose brutal fighters were feared in Ukraine, Africa and Syria, was eulogized Thursday by President Vladimir Putin, even as suspicions grew that the Russian leader was behind the crash that many saw as an assassination.

A preliminary U.S. intelligence assessment concluded the plane was downed by an intentional explosion. One of the U.S. and Western officials who described the assessment said it determined that Prigozhin was “very likely” targeted and that the explosion falls in line with Putin’s “long history of trying to silence his critics.”

The officials, who spoke on the condition of anonymity because they were not authorized to comment, did not offer any details on what caused the explosion, which was widely believed to be vengeance for the mutiny in June that posed the biggest challenge to Putin’s 23-year rule.

But Kremlin spokesperson Dmitry Peskov flatly rejected the allegations.

“Right now, of course, there are lots of speculations around this plane crash and the tragic deaths of the passengers of the plane, including Yevgeny Prigozhin,” Peskov told reporters during a conference call. “Of course, in the West those speculations are put out under a certain angle, and all of it is a complete lie.”

Prigozhin was listed among those aboard the plane.

Asked by The Associated Press whether the Kremlin has received an official confirmation of Prigozhin’s death, Peskov referenced Putin’s remarks from a day earlier: “He said that right now all the necessary forensic analyses, including genetic testing, will be carried out. Once some kind of official conclusions are ready to be released, they will be released.”

Britain’s Defense Ministry said the presumed death of Prigozhin could destabilize his Wagner Group of private military contractors.

His “exceptional audacity” and “extreme brutality” permeated the organization “and are unlikely to be matched by any successor,” the ministry said in a statement.

Wagner mercenaries were key elements of Russia’s forces in its war in Ukraine, particularly in the long fight to take the city of Bakhmut, the conflict’s most grueling battle. Wagner fighters also have played a central role projecting Russian influence in global trouble spots, first in Africa and then in Syria.

The jet crashed Wednesday soon after taking off from Moscow for St. Petersburg, carrying Prigozhin, six other Wagner members and a crew of three, according to Russia’s civil aviation authority. Rescuers found 10 bodies, and Russian media cited anonymous sources in Wagner who said Prigozhin was dead. But there has been no official confirmation.

President Joe Biden, speaking to reporters Wednesday, said he believed Putin was likely behind the crash.

“I don’t know for a fact what happened, but I’m not surprised,” Biden said. “There’s not much that happens in Russia that Putin’s not behind.”

Russian Deputy Foreign Minister Sergei Ryabkov took offense at that. “It is not for the U.S. president, in my opinion, to talk about certain tragic events of this nature,” he said today.

The passenger manifest also included Prigozhin’s second-in-command, as well as Wagner’s logistics chief and at least one possible bodyguard.

It was not clear why several high-ranking members of Wagner, who were normally exceedingly careful about their security, would have been on the same flight. The purpose of their trip to St. Petersburg was unknown.

Russian authorities have opened an investigation into the crash. The country’s Investigative Committee said today that it had recovered the plane’s flight recorders and that genetic testing was being used to identify the bodies.

Numerous opponents and critics of Putin have been killed or fallen gravely ill in apparent assassination attempts, and U.S. and other Western officials long expected the Russian leader to go after Prigozhin, despite promising to drop charges in a deal that ended the June 23-24 mutiny.

Prigozhin was outspoken and critical of how Russian generals were waging the war in Ukraine, where his mercenaries were some of the fiercest fighters for the Kremlin. For a long time, Putin appeared content to allow such infighting, but Prigozhin’s brief revolt raised the ante.

On June 23, his mercenaries swept through the southern Russian city of Rostov-on-Don and captured the military headquarters there without firing a shot. They then drove to within about 125 miles of Moscow and downed several military aircraft, killing more than a dozen Russian pilots.

Putin initially denounced the rebellion as “treason” and a “stab in the back,” but soon made a deal that saw an end to the mutiny a day after it began in exchange for an amnesty for Prigozhin and his mercenaries and permission for them to move to Belarus.

Belarusian President Alexander Lukashenko, who facilitated that deal, said today that Prigozhin never asked him for security guarantees. “I don’t have to ensure Prigozhin’s safety … the conversation was never in that vein,” he was quoted as saying by the state news agency Belta.

Lukashenko said he previously warned Putin of “an impending assassination attempt on Prigozhin,” according to Belta. Lukashenko told Belta he received “very serious information from the deepest sources” while on a recent trip to the United Arab Emirates and passed it on via the Russian ambassador in the UAE to Putin and the head of Russia’s FSB security agency.

Lukashenko later checked with Prigozhin, who confirmed Putin had warned him about the threat, according to Belta.

Since Prigozhin’s presumed death, unconfirmed reports said hundreds of Wagner’s fighters have fled Belarus. Relatives of Wagner fighters on one Telegram chat reported long lines for payments at a Wagner office in Russia’s southern Krasnodar region, the private force’s base.