- Navalny's office in Moscow said in a statement the group will already "no longer be able to work" as usual.
MOSCOW: Russian prosecutors on Monday suspended the activities of Alexei Navalny's regional offices, in a move his team said would essentially shut down the jailed opposition figure's movement.
The move comes after Navalny, President Vladimir Putin's most outspoken critic, ended a hunger strike last week that he had launched to demand proper medical treatment in prison.
A court in Moscow on Monday began proceedings into designating Navalny's Anti-Corruption Foundation (FBK) and its regional offices "extremist" after prosecutors requested they be added to a list run by Russia's Anti-Terrorism Committee.
"The activities of Navalny's offices and FBK were immediately suspended," FBK's director Ivan Zhdanov wrote on Twitter, attaching screenshots of a prosecutor's decision.
The Moscow City Court confirmed that the activities of the group's regional network were suspended, but clarified that prosecutors had the power to make the decision and said a final decision designating the group as extremist was due.
Navalny's office in Moscow said in a statement the group will already "no longer be able to work" as usual.
"It would be too dangerous for our employees and for our supporters," it said.
The team promised to continue fighting corruption, the ruling United Russia party and President Vladimir Putin "in a personal capacity".
"It will not be easy to fight, but we will win absolutely, because there are many of us and we are strong."
Germany condemned the order, with Chancellor Angela Merkel's spokesman Steffen Seibert saying that "using the instruments of fighting terror against politically undesirable opinions is in no way compatible with the principles of the rule of law".
Prosecutors on Friday said they had requested the extremism label for FBK and its regional offices because they are actively "creating conditions for the destabilisation of the social and socio-political situation."
It also accused them of working to alter "the foundations of the constitutional order".
There are currently 33 organisations on Russia's extremism list, including the Islamic State group and Al-Qaeda.
The groups are banned from operating in Russia and participating in their activities can result in lengthy prison terms.
FBK's members had already faced routine police searches and arrests for their activism, with the pressure ballooning since Navalny returned to Russia in January from Germany where he had been recovering from a poisoning attack.
The 44-year-old was arrested on his return and is now serving two-and-a-half years in a penal colony for violating parole terms on old fraud charges he says are politically motivated.
Most of his top allies have since been placed under house arrest or left the country, with several announcing publicly their were quitting FBK after prosecutors requested the extremism tag.
Earlier this month, a Russian court jailed FBK cameraman Pavel Zelensky for two years on charges of inciting extremism online. It cited two tweets saying that he hated Putin, among other officials, adding they did not deserve to be alive.
FBK routinely releases investigations into alleged graft by officials at all levels of government that are accompanied by YouTube videos that often go viral.
The group published its most notable probe after Navalny was arrested, accusing Putin of being gifted a luxurious property on the Black Sea coast.
The report helped spur mass anti-government protests over the winter, supported by FBK's nationwide network of regional offices.
Those offices also help organise Navalny's Smart Voting elections strategy, which calls for voters to cast their ballots for the candidate most likely to defeat Kremlin-linked opponents.
Navalny had staked out September's parliamentary poll as his next target.