Russia’s most significant opposition leader for the past decade, Alexei Navalny, has died in an Arctic Circle jail, the prison service said.
Gatekeepers News reports that Navalny was seen as President Vladimir Putin’s most vociferous critic.
Navalny was serving a 19-year jail term on charges widely considered politically motivated.
He was moved to one of Russia’s toughest penal colonies late last year.
The prison service in the Yamalo-Nenets district said Navalny had “felt unwell” after a walk on Friday.
He had “almost immediately lost consciousness”, it said in a statement, adding that an emergency medical team had immediately been called and tried to resuscitate him but without success.
“The emergency doctors declared the prisoner dead. Cause of death is being established.”
Navalny, 47, was last seen only a day ago, looking well and laughing during a court hearing via video link.
His lawyer Leonid Solovyov told Russian media he would not be commenting yet, although Navalny’s close aide Leonid Volkov wrote on X: “Russian authorities publish a confession that they killed Alexei Navalny in prison. We do not have any way to confirm it or to prove this isn’t true.”
Most of the Russian president’s critics have fled Russia, but Alexei Navalny returned in January 2021, after months of medical treatment.
In August 2020 he was poisoned at the end of a trip to Siberia with a Novichok nerve agent.
His team succeeded in flying him out to Germany for specialist treatment and on his return to Moscow he was immediately taken into custody.
He would never leave jail again in the next 37 months.
Navalny, who was 47, had long sought to challenge Vladimir Putin at the ballot box, but he was barred from running in the 2018 presidential election. Next month, Russia’s leader will stand unchallenged by any meaningful opposition.
Anti-war candidate Boris Nadezhdin was banned from standing in the election because of supposed irregularities found in the thousands of signatures submitted in support of his candidacy.
Navalny, whose opposition began in the form of an anti-corruption campaign, is the latest in a string of prominent Russian figures who have died while challenging Vladimir Putin’s rule.
Opposition leader Boris Nemtsov was shot dead on a Moscow bridge a stone’s throw from the Kremlin in 2015, and Wagner boss Yevgeny Prigozhin was killed in August 2023 in an unexplained plane crash weeks after leading his mercenaries in an armed mutiny.
