Sergei Udaltsov
Over the past few years Sergei Udaltsov has been locked up for several months, repeatedly going on hunger strikes that raised fears over his health. Reuters

Russian authorities launched a criminal investigation against Sergei Udaltsov, a left-wing activist, on Wednesday.

To members of Russia’s growing protest movement, the probe is just another example of the Putin administration’s refusal to tolerate dissent. But the Kremlin alleges that the charges are warranted: Udaltsov may have cooperated with Georgian nationals to promote terrorism in Russia.

Udaltsov, 35, heads the Left Front, a socialist organization. He has been an activist and vocal critic of President Vladimir Putin for years, and has been imprisoned several times for misdemeanors.

This time, authorities say they were tipped off by a documentary aired on a government-run television channel. The video allegedly shows Udaltsov working with Georgians to stoke riots in Russia.

Upon hearing about the documentary, Udaltsov was dismissive.

“I categorically deny receiving money sponsored from abroad, not to mention preparing any violent acts,” he said earlier this month, according to Russian news outlet Ria Novosti.

On Wednesday, security agents searched Udaltsov’s apartment and detained him briefly; he was released on the condition that he stay in Moscow.

Now, despite the leftist leanings that distance Udaltsov from some other dissenters in Russia, many opposition leaders are speaking up in his defense. It is a sign that Russian activists have grown bolder than ever before in recent months.

In March, thousands rallied to protest Putin's election to a controversial third term as president, with some international observers calling his victory illegitimate.

This summer, two high-profile cases of dissent made international headlines. In July, three members of the punk band Pussy Riot went on trial after being arrested for hooliganism in March; they had criticized Putin in a performance in a Moscow cathedral. Two of them were sentenced to serve two years in a brutal penal colony -- this month, they launched an appeal and lost.

Also on July 31, Russia's most high-profile human rights activist, Alexander Navalny, was charged by state investigators with embezzlement that allegedly occurred years ago. Navalny could face a decade in jail; he maintains that the charges are ridiculous and politically motivated. The investigations continue.

The Kremlin has been criticized for this apparent crackdown, but officials maintain that they are simply enforcing existing laws.

Vladimir Markin, a spokesman for Russia’s head federal investigator Aleksandr Bastrykin, said in a statement on Wednesday that Udaltsov should not expect leniency.

“I would like to draw the attention of those who thought that in our country it is possible with absolute impunity to organize mass disorders, to plan and prepare terrorist acts and other actions threatening the life and health of Russians,” he said, according to the New York Times.

“You underestimate the professionalism of Russia’s special services.”