Russian opposition leader Alexei Navalny is seen on a TV screen, as he appears in a video link provided by the Russian Federal Penitentiary Service in a courtroom of the Second Cassation Court of General Jurisdiction in Moscow, Russia in Oct. 2022. Alexander Zemlianichenko/Associated Press, File

MOSCOW — Imprisoned Russian opposition leader Alexei Navalny said Wednesday that he was facing new extremism and terrorism charges that could keep him behind bars for life, as authorities set the stage for a new trial against the Kremlin’s leading critic.

Navalny said by video link from prison during the hearing that the extremism charges which he rejected as “absurd” could land him in prison for 30 years. He noted that an investigator had told him he also would face a separate military court trial on terrorism charges that could potentially carry a life sentence, adding on a sardonic note that the charges imply that “I’m conducting terror attacks while sitting in prison.”

His top ally Ivan Zhdanov said investigators were trying to link the terrorism charges against Navalny to a bombing that killed a well-known Russian military blogger earlier this month.

Navalny, 46, who exposed official corruption and organized massive 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.

He initially received a 2½-year prison sentence for a parole violation. Last year, he was sentenced to a nine-year term for fraud and contempt of court. He is currently serving time at a maximum-security prison 250 kilometers (150 miles) east of Moscow.

The new charges against Navalny relate to the activities of his anti-corruption foundation and statements by his top associates. His ally Leonid Volkov said the accusations retroactively criminalize all the activities of Navalny’s foundation since its creation in 2011 and carry a potential punishment of up to 35 years in prison.

Navalny’s associate, Zhdanov, said Wednesday that investigators were revising the charges to link them to a bombing that killed Russian military blogger Vladlen Tatarsky at a St. Petersburg cafe earlier this month. The authorities described Darya Trepova, a 26-year-old St. Petersburg resident who was seen on video presenting Tatarsky with a statuette moments before the blast, as an active supporter of Navalny. They also accused Zhdanov and Volkov of making repeated calls for subversive activities in Russia.

An investigator told the court Wednesday that 11 other suspects facing extremism charges alongside Navalny have remained at large and have been put on an international wanted list.

Russian opposition leader Alexei Navalny is seen on a TV screen, as he appears in a video link provided by the Russian Federal Penitentiary Service in a courtroom of the Basmanny Court in Moscow, Russia, on Wednesday. Alexander Zemlianichenko/Associated Press

The new charges come as Russian authorities conduct an intensifying crackdown on dissent amid the fighting in Ukraine, which Navalny has harshly criticized.

Wednesday’s hearing at Moscow’s Basmanny District Court was held to discuss preparations for Navalny’s trial on the extremism charges. Navalny asked for more time to study the 196 case files.

The judge closed the session minutes after it opened, ruling that it should be held behind closed doors, because the case involved sensitive information.

“It’s an attempt to unlawfully restrict my ability to study the materials of the case and prevent anyone from knowing about it,” Navalny said before public access to the hearing ended.

The hearing ended with the judge giving Navalny 10 days to study his criminal case. No date for the trial has been set yet.

Navalny, who is President Vladimir Putin’s most prominent foe, has rejected the charges as a political vendetta and an attempt by Russian authorities to keep him out of politics for as long as possible.

His associates and supporters have become increasingly worried about his failing health. Earlier this month, they said Navalny had fallen ill with acute stomach pains and suspected that he was being slowly poisoned.

Navalny looked gaunt when he appeared via video link from prison, but he smiled and laughed as he warmly greeted journalists who were watching his appearance in court.

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.

His supporters have accused prison authorities of failing to provide him with proper medical assistance, using blindingly bright light in his cell and placing him next to a mentally unstable person.

Navalny said Tuesday that he had completed a 15-day stay in the punishment cell and was immediately ordered to spend another 15 days there.

The Russian authorities have ramped up their crackdown on dissent after Putin sent troops into Ukraine under new legislation that has effectively criminalized any public criticism of Moscow’s military action and independent reporting on the conflict.

Earlier this month, a Russian court convicted a top opposition figure, Vladimir Kara-Murza Jr., of treason for publicly denouncing Moscow’s war in Ukraine. He was sentenced to 25 years in prison.

Another prominent opposition figure, Ilya Yashin, was sentenced to 8½ years in prison last year on charges of spreading false information about the military.

On Wednesday, a court in Yekaterinburg opened a trial of the city’s former mayor, Yevgeny Roizman, on charges of discrediting the military that he rejected.

Roizman, a sharp critic of the Kremlin, is one of the most visible and charismatic opposition figures in Russia who enjoyed broad popularity as mayor of Yekaterinburg, Russia’s fourth-largest city of 1.5 million people in the Ural Mountains.

Last month, Roizman, 60, was ordered to spend 14 days in custody on separate charges of reposting material containing a reference to Navalny’s organization.

As part of a relentless clampdown, a Russian court last month convicted a father over social media posts critical of the war and sentenced him to two years in prison. His 13-year-old daughter, who drew an antiwar sketch at school, was sent to an orphanage.

On March 29, Russia’s security service also arrested Evan Gershkovich, an American reporter for The Wall Street Journal, on espionage charges that he, his employer and the U.S. government have rejected. Gershkovich is the first U.S. correspondent since the Cold War to be detained in Russia on spying charges, and his arrest rattled journalists in the country and drew outrage in the West.