Alexei Navalny, imprisoned Putin opposition leader, has died, Russia officials say

Alexei Navalny, the fiercest Russian President Vladimir Putin critic, has died in prison, Russian authorities said Friday. He was 47.

He crusaded against official corruption and led massive anti-Kremlin protests, 

The Federal Penitentiary Service said in a statement that Navalny felt sick after a walk Friday and lost consciousness.

A crew failed to revive Navalny and he died, authorities also said.

Navalny’s spokeswoman Kira Yarmysh said on X, the platform formerly known as Twitter, that the politician’s team had no confirmation of his death so far and that his lawyer was traveling to the town where he was held.

Navalny was serving a 19-year sentence on charges of extremism.

In December he was moved from his former prison to a “special regime” penal colony – the highest security level of prisons in Russia – above the Arctic Circle.