Alexei Navalny’s allies have shut down the jailed Russian opposition leader’s offices across Russia as the Kremlin intensifies its crackdown on political opponents.

Navalny’s chief of staff Leonid Volkov said in a message to supporters on Thursday that the offices’ work was “impossible in their current form” after prosecutors moved to declare them “extremist.” A court ruling confirming this designation would cut them off from funding and could result in 10-year prison sentences for staff.

The Kremlin is moving to stamp out Navalny’s network of supporters after he returned to Russia in January from Germany, where he was recovering from a nerve agent poisoning he and western governments have blamed on the Kremlin.

The anti-corruption politician was arrested on arrival and sentenced to two years in a notoriously harsh prison colony for missing parole meetings — including some while he was in a coma in Germany recovering from the poison.

Navalny’s health became a major sticking point in Moscow’s geopolitical stand-off with the west as he went on a three-week hunger strike to demand independent medical care for severe back and nerve pain.

On Thursday, a gaunt, shaven-headed Navalny made his first public appearance since his jailing via video link at an appeal against a separate February conviction for defaming a second world war veteran.

Though he said he “looked like a horrible skeleton” as he recovered from the hunger strike, Navalny joked with his wife Yulia and issued a fiery denunciation of Putin’s regime in court.

“This trial is all about how your naked king stole the victory banner and is trying to make a string bikini out of it,” Navalny said. “This is a government of occupants and traitors [ . . .] because you and your naked king are realising the plan you read about in history books: that Russia must be captured and Russians must be turned into slaves deprived of all their wealth, education, healthcare and any hope for the future.”

Navalny’s regional network, set up during a cross-country campaign for president in 2017, was key to organising mass nationwide protests for his release earlier this year. The Kremlin responded with a crackdown under which much of Navalny’s movement’s senior leadership fled to Europe, while leaders of the regional network faced arrest and violent intimidation.

Authorities are also exploring charges against Navalny, his chief of staff Volkov, and Ivan Zhdanov, the head of his Anti-Corruption Foundation, for “founding a non-profit organisation that infringes on citizens’ dignity and rights,” according to court documents the group published on Thursday.

The obscure law, which is intended to criminalise cults, has only been used against 14 people in the past 11 years and carries a sentence of up to four years in prison. The potential charges are separate from a money-laundering case against Navalny’s organisation, which was used as justification for searches at more than 250 addresses in 2019.

Volkov, who fled to Lithuania after the 2019 charges, said that the likely extremism ban — which a Moscow court is due to rule on next month — meant that Navalny’s 37 remaining offices would close. But he predicted that many of the Navalny movement’s 250 staffers would continue their activism in other forms. “You and I sowed seeds of freedom all over Russia. They’ll sprout and grow,” he said.