Moscow: Police armed with assault rifles raided the homes of Russia’s top protest leaders on Monday in a show of force on the eve of a mass Moscow rally against President Vladimir Putin’s rule.

The coordinated security sweep in the early hours of a public holiday targeted the homes of a new brand of young Russian politicians who analysts believe represent the biggest threat to ex-KGB spy Putin’s 12-year rule.

Officers beat down the doors of the increasingly popular anti-corruption blogger Alexei Navalny as well as media celebrity and more recent Putin critic Ksenya Sobchak.

Others on the list included Sergei Udaltsov — an outspoken ultra-leftist who stages periodic hunger strikes to protest his repeated arrests — and the far more moderate democracy campaigner Ilya Yashin.

Russia’s powerful Investigative Committee said 10 raids were being conducted in all as part of a probe over a previous demonstration “that ended in mass disturbances.”

A so-called “March of Millions” that drew 20,000 people in Moscow on May 6 ended in the arrest of hundreds after bloody clashes broke out between protesters and police on the eve of Putin’s inauguration to a third term.

Navalny and the nine others face up 10 years in prison if they are charged and convicted of organising mass disturbances. The protest movement blames police for the violence and calls the charges political.

The May 6 unrest sparked a stiff response from the Kremlin that saw Putin on Friday sign into law legislation dramatically raising fines for those who break the already restrictive laws on organising and holding rallies.

The highest penalty for individuals has been raised to 300,000 rubles ($9,000, Dh 33,048) — higher than for any other administrative offence and almost equivalent to Russians’ average annual salary.

Rights activists said Russia’s security agencies were trying to intimidate the nascent movement and prevent mass attendance in order to avoid embarrassing Putin just a month into his third term.

City authorities have authorised up to 50,000 people to take part in a demonstration and subsequent rally on Tuesday at the site of a December protest against that month’s fraud-tainted parliamentary polls.

“They are trying to disrupt the ‘March of Millions’ and make sure fewer people come,” human rights campaign Lev Ponomaryov told Interfax.

He argued that the raids and stiff new penalties would only energise the protest movement and give it the urgency it appeared to be losing after Putin’s dominant win in March 4 presidential elections.

Police had in previous days detained 12 people in connection with the May march.

The protest leaders’ representatives said the raids were unexpected and similar to those conducted in far more serious cases involving grave crimes.

Navalny’s attorney Olga Mikhailova told Moscow Echo radio that “around 15 policemen burst” into his Moscow apartment on Monday morning and presented him with a search warrant.

“Initially, they tried to break down the door,” she said.

The radio station’s deputy editor reported from Sobchak’s apartment building that armed police officers were stationed at the entrance and preventing others from getting in.

Udaltsov said he had been ordered to appear for questioning on Tuesday only an hour before the new demonstration was due to begin.

“They want to keep me from taking part,” Udaltsov told Interfax.

The Investigative Committee later confirmed that all those targeted would have to appear for questioning on Tuesday afternoon.