The Kremlin says Western suggestions Russian mercenary boss Yevgeny Prigozhin had been killed on its orders were an "absolute lie" while declining to definitively confirm his death, citing the need to wait for test results.
Russia's aviation authority has said Prigozhin, head of the Wagner mercenary group, was on board a private jet that crashed on Wednesday evening northwest of Moscow with no survivors.
President Vladimir Putin sent his condolences to the families of those killed in the crash on Thursday and spoke of Prigozhin in the past tense, breaking his silence after the incident that occurred exactly two months to the day after Prigozhin led a failed mutiny against army chiefs.
Putin cited "preliminary information" as indicating Prigozhin and his top associates in the Wagner mercenary group had all been killed.
While he praised Prigozhin, Putin said he had also made some "serious mistakes."
Western politicians and commentators have suggested, without presenting evidence, that Putin ordered Prigozhin to be killed to punish him for launching the June 23-34 mutiny against the army's leadership - the biggest challenge to Putin's rule since he came to power in 1999.
Kremlin spokesman Dmitry Peskov said the accusation and many others like it were false.
"There is now a great deal of speculation surrounding this plane crash and the tragic deaths of the plane's passengers, including Yevgeny Prigozhin," Peskov told reporters.
"Of course, in the West, all this speculation is presented from a well-known angle.
"All of this is an absolute lie, and here, when covering this issue, it is necessary to base yourself on facts.
"There are not many facts yet.
"They need to be established in the course of investigative actions."
Earlier on Friday, Russian Deputy Foreign Minister Sergei Ryabkov had scolded United States President Joe Biden for expressing his lack of surprise that Prigozhin had been killed in a plane crash, accusing Biden of disregarding diplomatic norms.
Russian investigators have opened a probe into what happened, but have not yet said what they suspect caused the plane to suddenly fall from the sky northwest of Moscow.
Nor have they officially confirmed the identities of the 10 bodies recovered from the wreckage.
Asked if the Kremlin had received official confirmation of Prigozhin's death, Peskov said: "If you listened carefully to the Russian president's statement, he said that all the necessary tests, including genetic tests, will now be carried out."
Official results would be published "as soon as they are ready", he said.
Peskov, who said Putin had not met Prigozhin recently, also said it was unclear how long the tests and investigative work would take.
It was therefore impossible to start talking about whether Putin would attend Prigozhin's funeral, Peskov said in answer to a question on the subject.
"There are no dates for the funeral yet," he said.
"It is impossible to talk about it at all.
"The only thing I can say is that the president has a rather busy schedule at the moment."
Russia's Baza news outlet, which has good sources among law enforcement agencies, has reported investigators are focusing on a theory that one or two bombs might have been planted on board the plane.
Asked about the future of the Wagner Group, which has a series of lucrative contracts across Africa and a contingent in Belarus training the army there but now appears leaderless, Kremlin spokesman Peskov was concise.
"I can't tell you anything now," he said.
"I don't know."