Melekhovo (Russia) | A Russian court on Monday opened a new trial of imprisoned Russian opposition leader Alexei Navalny that could keep him behind bars for decades.

The trial is taking place at a maximum security prison in Melekhovo, 250 kilometers (150 miles) east of Moscow, where Navalny — the Kremlin's arch foe — is serving a nine-year sentence for fraud and contempt of court.

Navalny, 47, who exposed official corruption and organised major anti-Kremlin protests, was arrested in January 2021 upon returning to Moscow after recuperating in Germany from nerve agent poisoning that he blamed on the Kremlin.

Navalny has said that the new extremism charges, which he rejected as “absurd”, could keep him in prison for another 30 years. He said an investigator told him that he would also face a separate military court trial on terrorism charges that could potentially carry a life sentence.

The new trial comes as Russian authorities are conducting a sweeping crackdown on dissent amid the fighting in Ukraine, which Navalny has harshly criticised.

The Moscow City Court, which opened the hearing Monday at Navalny's IK-6 prison, didn't let the media into the room and they watched the proceedings via video feed from a separate building. Navalny's parents were also denied access to the courtroom and followed the hearing remotely.

Navalny, clad in his prison garb, looked gaunt but spoke emphatically and gestured energetically as the trial got underway.

The new charges against Navalny relate to the activities of his anti-corruption foundation and statements by his top associates. His allies said the charges retroactively criminalise all the activities of Navalny's foundation since its creation in 2011.

One of Navalny's associates, Daniel Kholodny, was relocated from a different prison to face trial alongside him.

While imprisoned, Navalny has spent months in a tiny one-person cell, also called a “punishment cell”, for purported disciplinary violations such as an alleged failure to properly button his prison robe, properly introduce himself to a guard or to wash his face at a specified time.

Navalny's associates and supporters have accused prison authorities of failing to provide him with proper medical assistance and voiced concern about his failing health.