Russian opposition leader Alexei Navalny, known as a staunch critic of President Vladimir Putin, has died suddenly in prison. Russian authorities confirmed his death on Friday (February 16).

His mother Lyudmila cannot accept the fact that Navalny fell ill and died. In a Facebook post, he wrote that he was last seen on February 12. Navalny was then 'alive, healthy and happy'. He also writes that he does not want to hear any sympathy from anyone in this incident.

Jail authorities said that he fell ill suddenly while traveling in the jail. He died from that illness. The investigation into the death of the Russian opposition party leader has already started.

Kremlin spokesman Dmitry Peskov said, "There is no information yet on why and how Navalny died." An investigation has already been started to find out the reason as per the current rules of the jail.

Navalny has been imprisoned since 2021. He is known as a staunch critic of President Putin. He was also considered a rival of Putin. Navalny was sentenced to 19 years in prison in 2023 on charges of inciting and financing extremism. Navalny was eventually held in a penal colony in Siberia.