Russia on Monday ordered jailed Kremlin critic Alexei Navalny’s network of regional activist groups to stop their activities as a court reviews a request to outlaw them and his Anti-Corruption Foundation, representatives of the groups said.

Moscow’s state prosecutors have asked the court to label the groups “extremist”, a step that would effectively force the activist network set up by President Vladimir Putin’s most high-profile opponent to stop campaigning and push them underground.

At a preliminary hearing on Monday, prosecutors asked the Moscow court to prohibit the groups from taking part in elections, organising protests or publishing anything online, said Leonid Volkov, an associate of Navalny.

A court ruling that the groups are “extremist” would give Russian authorities the legal power to hand down jail terms to activists and freeze the groups’ bank accounts.

Navalny’s regional campaign offices, which he began opening in 2017 as he announced a bid for the presidency before he was barred from standing election, said they would stop posting anything on social media and were suspending operations.

“Unfortunately, we can no longer work in the old format. It’s not safe for staff and our supporters,” said his group in St Petersburg. Similar messages were posted by several others.

The hearings are being held behind closed doors as authorities have classified some of the case details, said lawyer Ivan Pavlov, whose legal team is handling the case. The next hearing is due on Thursday.

“We all understand perfectly that there is no extremism in (our) work... The extremism allegation is being used purely as a pretext for political repression,” Volkov said.

The prosecutor has accused Navalny’s groups of plotting to destabilise the political situation and working to promote a popular revolution.

The Kremlin declined to comment on the action against Navalny on Monday.

Navalny was jailed in February for two and a half years for parole violations on an earlier conviction that he called politically motivated. On Friday, he said he would start gradually ending a hunger strike after getting medical care.

Despite his jailing and the extremism case, Navalny’s allies hope to disrupt parliamentary elections in September with a “smart voting” strategy in which they will call on Russians to back politicians running against the ruling United Russia party.

“We have time, desire and strength to restructure our work... and to beat United Russia,” said Volkov.

Tens of thousands of people took to the streets across Russia on Wednesday in support of Navalny and more than 1,800 were detained.