Imprisoned Russian opposition figure Alexei Navalny has died on Friday (Feb. 16).

The Russian prison service said that the 47-year-old Kremlin critic allegedly collapsed and lost consciousness while he was incarcerated at a penal colony in Kharp in Russia's Arctic region, where he was serving a long jail term after returning to Russia in 2021.

"The facility's medical workers immediately arrived at the scene and an emergency medical team was called in," the prison service said in a statement, adding that causes of death were being established.

"All necessary resuscitation measures were carried out, which did not yield positive results. Doctors of the ambulance stated the death of the convict."

The cause of death remains unknown and might not be properly verified.

Read Also: Allies Fear Putin Critic Alexei Navalny Killed by Kremlin After Suddenly Vanishing From Penal Colony

Kremlin Critic Alexei Navalny Dies in Prison
(Photo: VERA SAVINA/AFP via Getty Images)

Navalny's supporters said they are still confirming if he actually died but speculated that he might have been killed.

Navalny rose to prominence in the late 2010s by criticizing Russian President Vladimir Putin and the Russian elite, whom he accused of vast corruption, greed, and lavishness.

His death came just weeks before an election that would see Putin, who was also informed of Navalny's death, remain as president.

This is a developing story. Please follow HNGN for more updates.

Related Article: Russian Opposition Alexei Navalny Found in Siberian Prison Two Weeks After Being Reported Missing