Russia may label Navalnys opposition networks as extremists groups. Even T-shirts could be outlawed.

The evidence to be used in the case is itself a state secret. Navalny's attorney has been told he will get access to the file shortly beforehand, according to Navalny ally Ivan Zhdanov.

If the court sides with the prosecutor's general request - declaring Navalny's political group and his Anti-Corruption Foundation to be extremist organizations - it would put them alongside the Islamic State, al-Qaida and the Taliban in the eyes of Russian authorities.

The rights group Amnesty International said it would be "one of the most serious blows for the rights to freedom of expression and association in Russia's post-Soviet history."

Even selling refrigerator magnets or wearing T-shirts with Navalny's slogan "Russia will be happy" could bring jail time. Navalny's team members could face six years in jail if they continued to work.

Putin foe Navalny once described prison life with dark humor. Now his messages are just dark.

Donating to Navalny's crowdfunded organizations would be akin to supporting terrorists, with penalties of up to 10 years in jail. Retweeting previous videos by Navalny's group, exposing the corruption of Russian politicians and bureaucrats, could also mean prison.

Already, Russian authorities have barred Navalny and many of his allies from contesting elections and made it a crime to call unauthorized protests or repeatedly participate in them. Many have fled into exile to avoid jail.

The court ruling takes to another level President Vladimir Putin's efforts to stamp out Navalny's influence.

Navalny, poisoned by a chemical nerve agent in August and jailed in February, announced an end to a 24-day hunger strike Friday after medical warnings he was facing death. On Wednesday, thousands of protesters across Russia took to the streets to call for Navalny's release.

Opposition activists draw parallels between Putin's increasingly tight grip and Soviet-style rule dominated by security officials and preoccupied with staying in power, amid growing public dissatisfaction over declining real wages and rising food prices.

"It reminds me of Soviet trials when someone was declared a spy or foreign agent and then there would be a secret closed trial," said Zhdanov, director of Navalny's Anti-Corruption Foundation, who fled the country earlier this year. "Putin is trying to take Russia back into the Soviet past."

Banning the organization as extremist "would open the gate to mass repressions. The authorities really want to destroy us because our activity is now making them vulnerable and they feel it," he said.

Putin and his government see themselves as Russia's true patriots and state media disparages Navalny a "Nazi" paid by foreign powers to ruin the country.

But the struggle underway in Russia is about two competing views of the country: one outward-facing and democratic, the other inward-looking, increasingly isolated and paranoid, forcing some young scientists, computer experts and engineers and others to immigrate to freer countries.

"It would not be safe for our staff and people who work for us to continue. Of course, we would have to reformat certain parts of our activity, but we are not going to stop," said Zhdanov.

Russian flags are stacked in one corner in Navalny's headquarters in Tomsk, the Siberian city where he was poisoned last August - an attack he blames on Russian agents acting on orders from Putin. The Kremlin denies any link.

Head of the regional headquarters Ksenia Fadeyeva, 29, is one of two Navalny Tomsk team members elected to the local council last year. On the wall in the office is a large map with all of the city's electoral districts marked out in pen and numbered.

"I love my country, but I know something is wrong here," she said. "I don't want to just sit here and do nothing. I want to change things."

Police have already raided many of Navalny's regional offices in recent weeks and arrested dozens of staff.

"We all know what risks we are facing. They can bring in new criminal cases or absurd charges. They will do their best to ruin our lives. We understand what might happen, but we cannot think about that too much or we would go crazy," she said.

Fadeyeva did not comment on what could happen if the organization is banned.

Tomsk colleague Andrei Fateyev was sentenced to 30 days in jail over Wednesday's protest in Tomsk.

"It's dangerous in Russia in general, whether you are a businessman or a politician or an activist," said Fateyev in an interview earlier this month.

But he believes "Russia will change."

"The goal of the regime is to hang onto power . . . But I don't believe they have the ability to cement their power, as they are trying to do now," he said.

Maria Alyokhina, a member of the political activist punk rock group Pussy Riot who was jailed for nearly two years over an anti-Putin protest in 2012 in Moscow's Christ the Savior Cathedral, said the crackdowns on dissent and jailing activists are now "part of everyday reality" in Russia.

"It happened in small steps, closing everything down," said Alyokhina, who is now under house arrest, is awaiting trial over her role in January protests in support of Navalny. "All these crazy laws on naming [nongovernment organizations] as foreign agents and people as foreign agents, and the huge fines and imprisonment," she added.

Designating Navalny's organizations as extremists "means that if you post a link to them, you can go to jail. What it means is that is that a big part of the country can be jailed. We are all illegal," said Alyokhina, who spent 12 hours a day, six days a week in prison sewing police and army uniforms. "It's Stalin's principle."

One 80-year-old Muscovite who joined a mass protest in support of Navalny on Wednesday feared Russia is heading into a form of authoritarian worse than that of the Soviet era.

After the Soviet Union collapsed, "we expected a brighter future. But we missed the moment when there was openness and this ability to speak up and express your opinion to do something," said Galina, who spoke on the condition that her surname not be used out of fear of repercussions. "Now we have this new control where the secret services are repressing everyone."