Under the terms of his house arrest, Udaltsov must stay at his home until April 6 and is banned from using the telephone or Internet. He may only speak to his family, his lawyers and investigators.

The 35-year-old leader of the Left Front, who until now has remained under travel restrictions that prevented him from leaving Moscow, faces 10 years in prison if a probe leads to a conviction.

Authorities opened a probe after state-controlled television broadcast a documentary in October that alleged Udaltsov was plotting a violent uprising against Putin’s government.

Udaltsov denies the accusations.

Before appearing in court, he told the media: “In my opinion nothing has changed that justifies putting me under house arrest.”

“I responded to all the investigators’ summons and I did not leave Moscow,” he added.

Russia’s investigative committee had said Friday that Udaltsov was being uncooperative with authorities.

“Sergei Udaltsov has not lived where he is registered for a long time, his mobile phones are often switched off, making it more difficult to summon the accused by the investigator,” the committee said in a statement.

The committee said that Udaltsov “continues to commit illegal acts”, saying the activist had taken part in an unauthorised protest in January where he had called on demonstrators to “launch unlimited protest action”.

Udaltsov’s lawyers said they would appeal against the decision.

One of the most radical voices in the protest movement, the shaven-headed activist rose to prominence during unprecedented protests against Putin’s 12-year political dominance in the winter of 2011, and has been one of the key speakers at opposition rallies.

He is the first prominent opposition leader to be put under house arrest since those protests – a sign that the Russian authorities may be preparing to ramp up pressure on the opposition as they seek to cauterise dissent.

Another opposition activist, Ilya Yashin, described the arrest as “unpleasant news but pretty much expected”.

“Arrests, searches and questioning of opposition figures by the authorities is becoming the norm now,” he told Moscow’s Echo radio. “Their methods are becoming harsher.”

A total of 19 people are being prosecuted for last year’s events, 12 of whom are in pre-trial detention. They each risk 10 years in jail.

Two of Udaltsov’s allies have already been detained and charged in the probe, including Leonid Razvozzhayev, an aide to an opposition parliamentary lawmaker.

Razvozzhayev’s case raised concern internationally after he said he was kidnapped in Ukraine and forced back to Russia, where he was detained and tortured.

He told rights groups that he admitted to the charges of causing mass unrest under duress and claims his family was given death threats.

Anti-corruption blogger Alexei Navalny was also detained but later released.

According to the non-government organisation Human Rights Watch, Russian civil society was subject last year to the worst repression since the fall of the Soviet Union in 1991.