Russian President Vladimir Putin has offered his condolences to the families of victims a plane crash that killed mercenary boss Yevgeny Prigozhin and several top brass of the notorious paramilitary group Wagner.

Putin broke his silence Thursday on the incident in televised comments describing Wednesday's crash as a "tragedy."

Prigozhin was registered on the plane that was carrying nine others who are also presumed to have died.

Wednesday evening's crash took place exactly two months after Prigozhin led a rebellion against Moscow's top military brass, considered by some observers to have been the biggest threat to Putin's long rule.

Although Moscow opened a probe into violations of air traffic rules, investigators have been silent since, as speculation of a possible assassination has grown.

Ukraine's President Volodymyr Zelenskyy insisted Kyiv had nothing to do with the incident.

"I think everyone knows who this concerns," he said, in what appeared to be a reference to Putin.

"There is a court in The Hague, there is a court of God. But Russia has an alternative (court) – President Putin," he said when asked again about the air crash later Thursday.

A 'common cause'

When Putin broke his silence Thursday, he paid a qualified tribute to the mercenary boss and the paramilitary group he led.

"I knew Prigozhin for a very long time, since the early 90s. He was a man of complicated fate, and he made serious mistakes in his life, but he achieved the right results," Putin said.

In an address to Russians during the Wagner rebellion on June 23-24 in which he warned against "civil war," Putin had called Prigozhin – once his ally – a "traitor."

But on Thursday, he said the Wagner members who had died in the crash had made a "significant contribution" to Moscow's offensive in Ukraine.

They had shared a common cause, Putin said, adding: "We remember that, we know that, and we will not forget that."

He said the investigation into the crash would take time, but added: "It will be conducted in full and brought to a conclusion."

Chechen strongman and Putin ally Ramzan Kadyrov paid tribute to Prigozhin's "iron character" in a message on Telegram.

But he added: "Recently he either did not see or did not want to see the full picture of what is happening in the country."

'Reasonable doubts'

Some Western leaders expressed doubts that the crash had been an accident.

"There's not much that happens in Russia that Putin's not behind," said U.S. President Joe Biden, after having said he did not know what happened.

France saw "reasonable doubts" about the crash, while Germany said it followed a pattern of "unclarified" fatalities in Russia.

German Foreign Minister Annalena Baerbock said it was suspicious that "a disgraced former confidant of Putin suddenly, literally falls from the sky two months after he attempted a mutiny."

Even influential pro-Kremlin figures, such as state television personality and Putin ally Margarita Simonyan, seemed to suggest that it could have been an assassination.

"Among the versions that are being discussed (about the crash) is that it was staged. But personally, I'm leaning toward the more obvious one," she said on social media.

Russia's aviation authority published the passenger list for the Embraer private jet late Wednesday.

It included Prigozhin and his right-hand man, Dmitry Utkin, a shadowy figure who managed Wagner's operations and allegedly served in Russian military intelligence.

Russian police patrolled the crash site near the village of Kuzhenkino, some 350 kilometers (220 miles) north of Moscow in the Tver region.

One woman living near Kuzhenkino said her neighbour had heard a roar and saw "sparkling from the plane," accompanied by fire.

"A neighbour ran up to me with shaking hands and when we went to the window I saw only one mushroom (cloud from the explosion), a black cloud," she said in video published by state-run news agency RIA Novosti.

'Real patriot'

Video verified by AFP from the scene appeared to show the Embraer Legacy plane in a plume of white smoke as it fell from the sky.

The Flightradar24 tracker website said the plane flying from Moscow to St. Petersburg appeared on their radar until the last 30 seconds and descended "dramatically" at around 3:20 p.m. GMT.

Some Wagner-linked Telegram channels initially suggested the plane had been shot down by Russian air defense, on a day when Kyiv struck Russia with more drone attacks.

Prigozhin appeared to enjoy some popularity in Russia.

He appealed to nationalist-leaning Russians – also suspicious of the army leadership during the Ukraine offensive – who embraced his tough-guy style.

Some even speculated that he would take part in the 2024 presidential election, which is expected to extend Putin's rule until at least 2030.

"He was one of the few real patriots in our country," Pavel Zakharov said as he laid flowers at Wagner's headquarters in St. Petersburg.

Many Russians eagerly awaited Prigozhin's outspoken, often expletive-laden social media videos, a sharp contrast to the tightly controlled narrative of Russian officials.

Ukrainians hope death 'true'

Wagner offices were still operating and even recruiting in Russia after Prigozhin's rebellion, which saw his men take over a military headquarters in the southern city of Rostov-on-Don and march on Moscow.

In Siberia, a region from where Wagner recruited heavily, people also laid flowers at the mercenary company's office in Novosibirsk.

But in Ukraine, where Wagner fighters were known for their exceptional brutality – including extrajudicial killings of their own men – many welcomed the news of Prigozhin's death.

"I feel really happy that this person died, if it is true," government worker Iryna Kuchina told AFP in Kyiv.

Prigozhin recruited tens of thousands of Russian convicts to fight in Ukraine, often thrown into the front line.

Wagner's future without Prigozhin remained unclear.