Russia's anti-Putin opposition launched online nationwide polls on Saturday to elect leaders of its ten-month-old protest movement but voting was disrupted early on by a massive cyber attack.

More than 165 000 Russians had registered to vote electronically to choose 45 people to run the opposition's Coordinating Committee, Russian news agency RIA Novosti reported.

Over 200 candidates, from opposition figurehead Alexei Navalny and fiery Left Front leader Sergei Udaltsov to little known civil activists are standing in the October 20-21 polls.

The committee will be comprised of civic activists, liberals, leftists and nationalists. The 45-seat council, in which 30 seats will go to civic activists while five will go to each of the three main opposition groups - liberals, left-wingers and nationalists.

The all-electronic voting is being held Saturday and Sunday, both online and at polling stations across a handful of Russian regions.

But the website for electronic voting was forced offline by hacking after polling began at 8:00 am (4:00 am GMT).

Electronic voting to the coordination council of Russia's street opposition was temporarily suspended Saturday over a hacker attack, the movement's central election committee said via Twitter Saturday.

"It is possible that the online voting has been affected by DDoS attacks," the committee said, referring to a Distributed Denial-of-Service attack, a common form of hacking that denies users access to targeted websites.

"The authorities are attempting to sabotage the polls," Navalny wrote on Twitter.

Voting also took place on Saturday in a central Moscow square, and queues formed outside around half a dozen white makeshift polling stations.

The square was surrounded by over ten police trucks and pro-Kremlin groups also picketed the entrance.

Russian state media has largely ignored or criticized the polls and parliamentary parties, with the exception of the Communists, have said they will not work with its leaders, RIA Novosti's report says.

Vote organizers said on Saturday Federal Security Service (FSB) agents had entered a polling booth in the Ural city of Chelyabinsk and briefly stopped people voting.

"Yesterday, the Kremlin's political analysts were telling us how insignificant our elections are. And today FSB agents are visiting our polling station," current committee chairman Leonid Volkov tweeted.

Navalny says the vote will provide the opposition with legitimacy that he says Russian President Vladimir Putin and the ruling United Russia party lack because of allegations of widespread electoral violations at the most recent presidential and parliamentary polls.

The vote is also intended to give a boost to the protest movement, which has lost momentum since Putin's presidential inauguration in May 2012.

Putin has mocked the unprecedented opposition to his almost 13-year-rule, calling protesters Western-backed, chattering monkeys. He also said the opposition has failed to set out clearly its demands and that it has no official representatives he can talk to.

Voting to the committee came just days after Udaltsov, the Left Front leader, was charged with organizing mass disorder – a charge that could see him face up to ten years behind bars.

Udaltsov was freed by investigators on Tuesday on a pledge not to leave Moscow, but his aide, Konstantin Lebedev, has been retained in custody.

The charges were based on grainy, low-quality footage aired by the state-run NTV channel of what the station said was Udaltsov discussing plans for a coup with a Georgian politician. Udaltsov says the footage is fake and the charges against him are "lunacy."

NTV journalist Alexei Malkin told a Moscow court last week that an "unknown Georgian" handed him a disc containing the footage as he was walking down the street.

"This is all revenge for our recent protests," Udaltsov told journalists on Saturday. "Everything is clear – this is a challenge to society and an attempt to launch a new wave of repression. If we don't stop it, we will face a long, political winter."

Navalny also faces up to ten years behind bars after investigators charged him with large-scale embezzlement earlier this year. The probe into the 2009 case had been closed twice without charges before it was reopened this summer.

A host of other opposition figures have faced legal problems since Putin's return to the Kremlin. But Putin has denied a crackdown against dissent is underway, saying last month that everyone must "comply with the law."