Alexei Navalny, Russia's most important opposition leader for the past decade, has died in a prison in the Arctic Circle, prison authorities have announced.
Navalny, considered President Vladimir Putin's most vocal critic, was serving a 19-year sentence on charges widely believed to be politically motivated.
Late last year, he was transferred to an Arctic penal colony, said to be one of Russia's toughest prisons.
Prison authorities in the Yamalo-Nenets region said Navalny “feeled unwell” after a walk on Friday.
The newspaper said in a statement that the man “lost consciousness almost immediately,” adding that emergency medical teams were immediately called and attempts were made to resuscitate him without success.
“Emergency doctors pronounced the prisoner dead. The cause of death is still being determined.”
Navalny's lawyer Leonid Solovyov told Russian media he would not comment yet, but Navalny's close aide Leonid Volkov said of X: “Russian authorities killed Alexei Navalny in prison. “We have no way of confirming or proving that.” This is not true. ”
Within minutes of prison authorities announcing Navalny's death, the international community praised the courage of President Vladimir Putin's biggest domestic opponent.
France said he paid with his life for resisting Russia's “tyranny” and Norway's foreign minister said Russian authorities bore grave responsibility for his death.
Putin's spokesman Dmitry Peskov said only that Navalny's death had been “reported to the president” during a visit to Chelyabinsk.
Most of the Russian president's critics have fled Russia, but Alexei Navalny returned home in January 2021 after months of treatment. In August 2020, he was poisoned with the nerve agent Novichok at the end of a trip to Siberia.
His team was able to fly him to Germany for specialist treatment, and upon his return to Moscow he was taken into custody. He never left prison again for the next 37 months.
Navalny had long sought to challenge Vladimir Putin at the polls, but was barred from running in the 2018 presidential election. Next month, the Russian leader will not bow to any serious opposition.
Anti-war candidate Boris Nadezhdin has been banned from running for office after fraud was found in thousands of signatures submitted in support of his candidacy.