Reports: Imprisoned Russian opposition leader Alexei Navalny dead

Imprisoned Russian opposition leader Alexei Navalny has died, say media reports. He was 47.

Navalny, who was known to be a fierce critic of Russian President Vladimir Putin, was serving a 19-year jail term. He was moved to Arctic penal colony, which is considered to be one of the toughest prisons, located in a region that is notorious for long and severe winters.

According to the prison service, he "felt unwell" on Friday and "almost immediately lost consciousness."

"The emergency doctors declared the prisoner dead. Cause of death is being established," the prison statement read.

According to Reuters, Russia's Investigative Committee launched a procedural probe into the death.

The press secretary Navalny, Kira Yarmysh, in a social media post said she is unable to confirm his death, and Navalny's lawyer was travelling to the prison where the Russian leader was serving his sentence.

Leonid Volkov, an aide to Navalny, too said they are unable to confirm his death.

Navalny, sentenced to prison on charges of extremism, had been in prison since January 2021, when he returned to Moscow after recuperating in Germany from nerve agent poisoning that he blamed on the Kremlin.

Before his arrest, he campaigned against official corruption, organised major anti-Kremlin protests and ran for public office.