Imprisoned Russian opposition leader Alexei Navalny dies

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.

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.