MOSCOW — A closed Russian court on Monday ordered opposition leader Alexei Navalny's headquarters and network of nearly 40 regional offices to suspend their activities while it considers whether to ban them, according to lawyers for his team.

Russian prosecutors asked the court to ban three organizations associated with the jailed Navalny, in a hearing in which much of the case file was secret, the lawyers said.

Navalny’s lawyers were given access to the prosecution file on the case only on the morning of the hearing. 

The suspension means that Navalny's main political network in the country has been barred from operating ahead of parliamentary elections in September.

The court also suspended a number of YouTube channels, Instagram and other social media sites associated with Navalny, stating that these websites contained extremist material and issued calls to participate in extremist activity and mass disorder.

A ban would be one of the most sweeping measures to repress freedom of speech and to destroy an opposition movement since the collapse of the Soviet Union 30 years ago, according to rights groups.

The court will decide Tuesday on whether to suspend the activities of the Anti-Corruption Foundation pending the court decision on the ban, as well as Navalny’s headquarters and regional offices.

Navalny’s Anti-Corruption Foundation, which prosecutors want to ban, has published hard-hitting reports on the alleged corruption of top Russian bureaucrats and officials from President Vladimir Putin on down. Among the reports was a video entitled “Putin’s palace. History of the world’s largest bribe,” which has been viewed on YouTube more than 116 million times.

Also being considered is the Navalny Headquarters, a network of nearly 40 regional offices in cities across Russia. A ban would mean employees of those offices could be jailed if they continued to work. The third organization that prosecutors want to ban is the Civil Rights Protection Organization.

One of the attorneys for Navalny’s organizations, Ivan Pavlov, said the case was unprecedented.

“We have never encountered a case where the fight against corruption has been called a threat to state security,” said Pavlov, who specializes in cases in which people are deemed to have disclosed state secrets or threatened state security.

He added that the case potentially impacted all Russians because it was against “everyone who supported the foundation, who sent donations, who watched the investigations.”

Pavlov said he would focus on ensuring the court released as much information as possible, which might be complicated by the presence of state secrets in the case files.

Pavlov tweeted a photograph of a green plastic bag containing a pile of papers more than a foot high — the documents related to the case that were not classified. According to lawyers, the papers weighed more than 22 pounds.

The Moscow prosecutor’s office said it submitted “exhaustive evidence” to the court Monday that the Navalny organizations were “destabilizing the sociopolitical situation in the country, including through calls for violent action, extremist activities, and mass unrest and through attempts to engage minors in unlawful activities.”

It said Navalny’s organizations were controlled by “foreign centers pursuing destructive designs with regard to Russia.”

Earlier this month, the prosecutor said Navalny’s organizations were trying to change the government and foment a “color revolution” operating “under the guise of liberal slogans.”

Another lawyer for the Navalny team, Valeria Vetoshkina, said the fact that the ban would allow the prosecution of any citizens who supported the three Navalny organizations contradicted the current constitution.

“We may have different views on the Anti-Corruption Foundation and the ideas that Alexei Navalny promotes in particular, but there is nothing that they do that would fall under the definition of extremism,” she said.

She added that the classification of court materials as state secrets raised questions of why.

“So far, it looks like an attempt to keep everyone from talking openly about this process,” she said.

Navalny is in jail serving a term of more than 2 ½ years in a case he calls political. He was arrested on his return from Germany, where he received treatment last year after being poisoned in August with a chemical nerve agent that Navalny, the United States and the European Union have blamed on the Russian state — a claim Russia denies.

Anti-Corruption Foundation investigator Maria Pevchikh said the hearing was crucial because it equated “the fight against corruption with extremism” and was only the beginning. “Don’t think it won’t affect you. It will. They just started with us.”

Amnesty International has called the ban requested by prosecutors an attempt to “fully shut down dissent.”

“If the courts label Navalny’s organizations ‘extremist’ and ban them, the result will likely be one of the most serious blows for the rights to freedom of expression and association in Russia’s post-Soviet history,” the organization said in a statement.

“This looming ban has far-reaching consequences for Russian civil society. Tens of thousands of peaceful activists and the staff of [Alexei] Navalny’s organizations are in grave danger — if their organizations are deemed ‘extremist’ they will be at imminent risk of criminal prosecution,” Amnesty International said.

Russian police have raided many of these offices and have arrested dozens of Navalny’s activists in recent weeks, banging on the doors of their homes in the middle of the night in some cases.