Alexei Navalny was a Russian lawyer and politician (File).
Alexei Navalny, the jailed Russian political leader who was a fierce critic of President Vladimir Putin, has been found dead at the federal prison in Russia's Yamalia, where he was serving his sentence.
"Navalny felt bad after a walk, almost immediately losing consciousness. Medical staff arrived immediately and an ambulance team was called. Resuscitation was carried out but did not yield positive results. Paramedics confirmed the death. Cause is being established," the prison said.
Mr Navalny was serving a 19-year jail term - to add to five other sentences totalling nearly 12 years - at the Arctic prison colony. The latest was delivered in August last year on extremism charges.
Mr Navalny - who rose to prominence over a decade ago after accusing Mr Putin of corruption - has said the charges against him have been fabricated to keep him in jail and out of active politics.
There is much about the 47-year-old lawyer's court cases and internment that is unknown, prompting criticism from the West the Russian government is suppressing its critics.
Alexei Navalny had been in jail since February 2021 - since recovering from an assassination attempt the year before. He was poisoned with a nerve agent in August 2020 while on a flight to Moscow.
He had to be evacuated from a Russian hospital to one in Berlin for his treatment.
After his recovery five months later, Mr Navalny returned to Russia, and was promptly arrested.
He was sent to jail for two-and-a-half years. Russian courts said he had violated the terms of a 2014 suspended sentence; authorities accused him of failing to report to them regularly in 2020.
His legal team pointed out the claim was ridiculous since Mr Navalny spent the year in Germany, recovering from the attempt on his life. He was also in a coma during this time.
The 2014 sentence was for allegations of embezzlement from a Russian subsidiary of a French cosmetics firm. The conviction was criticised by the European Court of Human Rights - which said the Russian government had to pay compensation - but was upheld by the Russian Supreme Court.
He was sent to a penal colony in central Russia's Vladimir region, which is 230km east of Moscow.
In March 2022 the sentence was increased by nine years, and he was moved to a new prison.
And, in August last year, he received the 19-year term for forming and funding extremist organisations and activities. That was months before Mr Putin began his re-election bid.
In fact, in December last year he was reported "missing" from prison.
He emerged days later at the Arctic jail - nicknamed "Polar Wolf" - in which he eventually died.
The prison change - secretive as is usually the case in Russia - came after the court ruled he be moved to a harsher facility, one that usually houses particularly dangerous prisoners.