Alexei Navalny, the most high-profile Russian critic of Vladimir Putin has been transferred from his prison and moved to an unknown location, a top aide said on Tuesday.

       “Where Alexei is now, and which colony he is being taken to, we don’t know,” Leonid Volkov, Navalny’s chief of staff, said in a statement on the Telegram app.

       Navalny is currently serving more than 11 years.He was jailed last year for two-and-a-half years and in March was sentenced to an extra nine years for fraud and contempt of court.

       Last month he was charged in a new criminal case faces an extra 15 years in jail on a charge of creating an extremist organisation and inciting hate towards the authorities.

       In March, Navalny denounced Russia’s invasion of Ukraine and called Putin an “insane tsar”.

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       “The war was intended to cover up the robbery of Russian citizens and divert their attention away from the country’s internal problems,” Navalny told a court hearing from behind bars.

       He has also claimed the invasion was “stupid” and “built on lies”.

       A long time critic of Putin and his corruption, Navalny was poisoned in 2020 with a nerve agent during a campaigning trip in Siberia, according to analysis conducted by multiple European medical institutions.

       With his life in danger he was subsequently rushed to Germany and after months of medical treatment in Germany, he was arrested for parole violations when he returned to Russia at the start of 2021.

       Russian President Vladimir Putin

       (EPA)

       Following the invasion of Ukraine, the Kremlin has accelerated its decades-long campaign to quash and silence Russia’s domestic opposition. Navalny has spoken out against the war, attacking Putin during a court appearance and calling the invasion “stupid” and “built on lies”.

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       Navalny had been serving his sentence at the prosaically-named Correctional Colony No. 2, a prison camp in Pokrov, 74 miles (119km) east of Moscow.

       Navalny’s political network has been largely dismantled since his jailing, having been banned as an “extremist” organisation. Senior aides and organisers have either been jailed or forced into exile.