Russian political leader Alexei Navalny has passed away in prison aged 47.

The prison service of the Yamalo-Nenets region, in North-Western Russia said in a that he “felt bad after a walk” and lost consciousness.

“Medical staff arrived immediately and an ambulance team was called. Resuscitation measures were carried out which did not yield positive results,” they added

Politically active since 2007, Navalny initially became an anti-corruption campaigner via his online blog – purchasing shares in state-owned oil business to access company records. He subsequently led numerous protests against the Kremlin, leading to arrests and short bouts in jail.

In 2017, his presidential campaign was blocked by officials due to a prior conviction in 2013. This led to even bigger protests, calling for the election to be boycotted.

Deeply disturbed and saddened by news of the death of Alexei Navalny.

Putin fears nothing more than dissent from his own people.

A grim reminder of what Putin and his regime are all about.

Let's unite in our fight to safeguard the freedom and safety of those who dare to… pic.twitter.com/YoIbS7XbdX

— Ursula von der Leyen (@vonderleyen) February 16, 2024

Navalny was hospitalised in 2020 and placed in a coma. Hospital tests discovered that he was poisoned by a Soviet-era nerve agent and he accused Putin of orchestrating the attack, which the Kremlin denied.

He was arrested once more in 2021 for breaking restrictions of a prior suspended sentence after had been brought to Berlin by Russian doctors following his hospitalisation. This sparked further protests amongst public. In 2022 Navalny was charged with embezzlement and handed a nine-year prison sentence.

World leaders have spoken out following his passing, with European Commission President  Ursula Von Der Leyen saying on social media that she was “deeply disturbed and saddened by news of the death.”

“Putin fears nothing more than dissent from his own people,” she added, describing the incident as a “grim reminder of what Putin and his regime are all about.”

Elsewhere, NATO Secretary General Jens Stoltenberg said that he was “deeply saddened and concerned about reports coming from Russia that Alexei Navalny is dead,” and that “Russia has some very serious questions to answer”.