The Kremlin's most prominent critic Alexei Navalny died Friday in an Arctic prison, said Russian authorities, announcing his death a month before an election poised to extend Vladimir Putin's hold on power.
Navalny's death after three years in detention and a poisoning which he blamed on the Kremlin deprives Russia's opposition of its figurehead at time of intense repression and Moscow's campaign in Ukraine.
Dissidents and Western officials blamed Putin and his government for the 47-year-old's death, which followed months of deteriorating health in harsh detention conditions.
"Alexei Navalny was tortured and tormented for three years... Murder was added to Alexei Navalny's sentence," Russian Nobel Peace Prize winner Dmitry Muratov was quoted as saying by the Novaya Gazeta newspaper.
Russian news agencies reported that medics from a hospital in Russia's far north spent more than "half an hour" trying to resuscitate Navalny, who reportedly lost consciousness after a walk.
The exiled team of Navalny said it had not been informed of his death and that a lawyer was headed to the Arctic prison colony where he was serving a 19-year term on an extremism conviction.
Navalny was Russia's most prominent opposition leader and won a huge following with his campaigning against corruption in Putin's Russia.
Russia's Investigative Committee said it had opened an investigation into the death.
Citing his spokesman, Russian news agencies reported that Putin had been informed of Navalny's death.
Putin -- who famously never referred to Navalny by name -- was on a visit to Chelyabinsk on Friday.
In footage of a meeting with workers in the Urals city published after the announcement of the death, he made no mention of Navalny.
Kremlin spokesman Dmitry Peskov told reporters he did not know any further details about the cause of death.
One of Navalny's lawyers, Leonid Solovyov, told the independent Novaya Gazeta paper that the Kremlin critic was "normal" when a lawyer saw him on Wednesday.
"On the decision of Alexei Navalny's family, I won't make any comments at all. We are now sorting things out. Alexei's lawyer was with him on Wednesday. Everything was normal then," he said.
In video footage of a court hearing from his prison colony on Thursday, Navalny was seen smiling and joking as he addressed the judge by video link.
Western governments and Russian opposition figures immediately said the Kremlin was responsible for his death.
German Chancellor Olaf Scholz said he had "paid for his courage with his life", while Britain's Prime Minister Rishi Sunak said his death was a "huge tragedy" for the Russian people.
The president of Latvia, a staunch opponent of Russia, said he had been "brutally murdered by the Kremlin".
"The Russian government bears a heavy responsibility," Norway's Foreign Minister Espen Barth Eide wrote on X, formerly Twitter.
"Alexei Navalny paid his life for resistance to a system of oppression. His death in a penal colony reminds us of the reality of Putin's regime," French Foreign Minister Stephane Sejourne said on X.
Ukraine, battling Russian forces, said Putin -- in power since 2000 -- is "afraid of any competition."
Navalny, who led street protests for more than a decade, became a household name through his anti-corruption campaigning.
His exposes of official corruption in Putin's Russia, posted on his YouTube channel racked up millions of views and brought tens of thousands of Russians to the streets, despite Russia's harsh anti-protests laws.
He was jailed in early 2021 after returning to Russia from Germany, where he was recuperating from a near-fatal poisoning attack with Novichok, a Soviet-era nerve agent.
In a string of cases he was sentenced to 19 years in prison on charges widely condemned by independent rights groups and in the West as retribution for his opposition to the Kremlin.
His return to Russia despite knowing he would face jail brought him admiration.
"I'm not afraid and I call on you not to be afraid," he said in an appeal to supporters as he landed in Moscow, moments before being detained on charges linked to an old fraud conviction.
His 2021 arrest spurred some of the largest demonstrations Russia had seen in decades, and thousands were detained at rallies nationwide calling for his release.
From behind bars he was a staunch opponent of Moscow's full-scale military offensive against Ukraine, and watched on, helplessly, as the Kremlin dismantled his organisation and locked up his allies.
Dozens of his top allies fled into exile and continued to campaign against the offensive on Ukraine and growing repression inside Russia.
Late last year Navalny was moved to a remote Arctic prison colony in Russia's Yamalo-Nenets region in northern Siberia.
The last post on Navalny's Telegram channel, which he managed through his lawyers and team in exile, was a tribute to his wife, Yulia Navalnaya, posted on Valentine's Day.
