Russian opposition politician Alexei Navalny has died in prison

Russian opposition politician Alexei Navalny has died in prison, according to Russian authorities. The ardent critic of President Vladimir Putin has been jailed since 2021.

In December, he was moved to a notorious artic penal colony, thousands of miles to the north-east of Moscow in Siberia.

A reason has not yet been given for his death, though prison authorities have said he felt unwell after a walk on Friday and then fell unconscious.

He had "almost immediately lost consciousness", the prison service said in a press release, 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, who campaigned against what he described as rampant corruption within Russia, was poisoned in 2020 in what Western laboratories later confirmed to be a nerve agent.

In his last public appearance from prison on 10 January, Navalny joked that he that he was yet to receive any Christmas mail, due to being "quite far away".

Navalny's lawyer Leonid Solovyov told Russian media he would not be commenting yet.