We are wrapping up the blog now, at the end of an historic, but peaceful day of mass protests across Russia.
The protests come three months before Putin, who was president in 2000-2008 and effectively remained the country's leader while prime minister, is to seek a third term in office.
Here's a summary of the events of the day:
• Russia saw the largest political event of its kind in nearly 20 years with tens of thousands of furious protestors rallying across the country against alleged electoral fraud.
• An estimated 50,000 people gathered in Moscow and 10,000 in St Petersburg. There were around 1,000 arrests on a day that passed off largely peacefully
• Protestors pledge to take to the streets again on December 24
• Protestors demand annulment of Sunday's election results; the resignation of the head of the election commission and an official investigation into vote fraud.
• They also want new democratic and open elections and registration of opposition parties
Mark Townsend tweets that the London protest over Russia's disputed elections is starting to disperse as night falls.
The head of the Russian election commission, Vladimir Churkov, could be heading for the chop, reckons Michael Idov, contributing editor of the New York magazine.
Less than 100 demonstrators were reported arrested across Russia, AP reports. This contrasts with the hundreds taken into custody at smaller protests in the first days after disputed election.
Police, who normally crack down fast and hard on any unauthorised gathering, even allowed a few hundred leftist radicals to conduct an unsanctioned protest on Moscow's Revolution Square just outside the Red Square.
The Interfax news agency reports that no one was arrested during the Moscow protest.
A Ministry of the Interior spokesman said: "The event passed without incident and no one was detained."
Mark Townsend has just sent through his dispatch about today's protest in London.
In London, more than 200 protesters are gathered outside parliament to vent their disquiet over the disputed polls.
Supporters sporting white ribbons have assembled in Westminster to chant "re-election, re-election". Some have travelled from as far away as Manchester, Bristol and Norwich. Most believe that the demonstrations in Moscow and across Russia herald the onset of change, a transfer of power from the political elite to the people.
Student Marina Issaeva, 22, from Moscow, said: "I've never protested in my
life, it's good to see so many young people also here.
"Something has started moving, it's unprecedented. We must make sure momentum is not lost."
Alexey Kovalev, 30, london-based editor of Snob, said the "excellent" turnout in central London was fuelled by fury.
'People are very angry. Look around, people want change.' As he spoke, more small groups joined the demonstration, including a group of Ukranians. Many of those gathered are waving placards, some carrying a portrait of Putin emblazoned with the accusation: "They stole our vote."
Others stated simply: "Fair vote for Russia."
Teaching assistant Dmitri Ponomaev, 30, said: "We are saying enough is enough."
Anastasia Vladimirova, 21, in London on a tourist trip from the Russian capital, added: "I hope we can change the system, something has to give but the politicians are very powerful."
Masked Russian protesters in London. Photograph: Alexey Kovalev
Here's a set of photos from the demonstration.
There was a folk carnival atmosphere to the end of the rally at Bolotnaya Square, writes Alexei Belovs.
People are drinking champagne from the bottle, beating the drums, dancing, Komsomolskaya Pravda reports.
When asked why men are drinking champagne, as it is not a manly drink, they told the Russian tabloid "because the mood is appropriate, and it's more fun than New Year. Most surprising - nobody was arrested!"
Miriam Elder has posted this video on Twitter of protesters dancing.
The protest in Ulyanovsk, the birthplace of Lenin, went ahead without the organisers, Alexei Belovs writes.
Konstantin Troshin (Drugaya Rossiya party) was attacked by a man. Slava Yemelyanov (Yabloko party) was arrested and brought to the head of the city's department of internal affairs. Oleg Loskutov was called into work under threat of being sacked. Despite this 500 people gathered at the city's Lenin Square.
A senior official from the United Russia party has told demonstrators to not to turn into "cannon fodder" and abide the law, writes Alexei Belovs.
Andrey Isaev, deputy secretary the ruling party's general council, promised to "hear out" the protesters, Russian news agency RBK reports.
Isaev added that people expressing their disagreement with the results of the elections "have a right to do so"
The Russian electoral commission has defended the disputed vote and rejected calls for a fresh poll.
Vice chairman of the Central Election Commission Stanislav Vavilov told the Interfax news agency they had approved the electoral process:
Elections were acknowleged as valid and there are no reasons for any other opinions. We see no reason for election revision.
My colleague Mark Townsend, who is at the London demo, tweets that there is a "sense of optimism" among the Russian protesters.
One of the demonstrators Anna Parigskaia told him: "There will be change definitely. If not this, the next election."
Here's a list of the official demands from the organisers of the Moscow protest:
1. Freedom for political prisoners
2. Annulment of the election results
3. The resignation of Vladimir Churov, head of the election commission, and an official investigation of vote fraud
4. Registration of the opposition parties and new democratic legislation on parties and elections
5. New democratic and open elections
Our Moscow bureau says that 7,000 people attended the protest in In St Petersburg.
Police detained 10 people en route from Vosstaniya Square to Pionerskaya Square.
The number of protesters at Pioneer Square in St Petersburg has now reached 10,000 according to organisers.
Russian dissident Boris Berezovsky has been talking to Sky News. He says the numbers protesting are very significant – previous protests have seen fewer than 5,000 on the streets.
Opposition politician Vladimir Ryzhkov, one of the organisers of today's Moscow rally, has announced there will be another protest on December 24, which he says will be twice as large.
My colleague Luke Harding is at the London demo in support of the Russian protests, which he says is the biggest ever protest against Putin held in the UK.
This is the biggest ever anti-Putin demo in Britain. These protests usually attract 15-20 people. There are 200-300 people here today. Everyone is saying that they think things are changing [with Russian politics].
There are some amusing banners – "Putin cheats at maths" and "Bastards – they stole my vote".
Russians in London protesting the election. Photograph: Alexey Kovalev
Alexey Kovalev, one of the organisers of the protest, says:
Nobody would have thought a month ago that we'd have this many people. There's a million people on the streets of Russia. It's a phenomenal turnout. The people are fed up with having their votes stolen. I do hope the Russian government comes to their senses.
My colleague Miriam Elder says all the protesters say they will continue demonstrating until their are fresh and fair elections.
She estimates there around 50,000 people at Bolotnaya Square. Hundreds of people are leaving but hundreds more are still arriving. She is walking over the bridge opposite the Kremlin, which is lined with hundreds of police.
The crowd is chanting, "We will come again". Nationalists have burned United Russia's flag.
The overall atmosphere is cheerful despite the snowfall, adds Alexei Belovs. Protesters are handing flowers to police. Some of the slogans on the banners include: "I did not vote for these bastards. I voted for other ones", "Do not hit me – I am here by an accident", "Send Putin to Azkaban"
Here's a link to the Guardian gallery of today's protest in Moscow.
Here's a link to the Facebook group for the London demonstration in support of the protests in Russia.
Russian state television channel NTV has described the rally on Bolotnaya Square as "grandiose", writes Alexei Belovs.
The rally is the main item on its official website. NTV has also reports that one of its journalists, Alexei Pivovarov, refusing to host a news programme if teh channel did not cover the rally.
Here's a video from the square.
AP has filed a report on the Moscow protest, reporting there are between 25,000 and 40,000 people gathered at Bolotnaya Square.
"The falsifications that authorities are doing today have turned the country into a big theater, with clowns like in a circus," said Alexander Trofimov, one of the early arrivals for the protest at Bolotnaya Square.
"I don't think any citizen of the country can say he is very happy with anything. We don't have an independent judiciary, there is no freedom of expression all this combined creates a situation where people are forced to protest," said demonstrator Albert Yusupov, who was dressed in civilian clothes but identified himself as a member of the Russian army.
By the time the rally started, the square and adjacent streets were packed shoulder-to-shoulder with protesters braving intermittent wind-blown snow. Police said there were at least 25,000, while protest organisers claimed 40,000.
Here's another photo from Twitter that shows how packed the square is. This one shows how the crowd has spilled over onto the bridges leading to the square.
Hardcore Nationalists have set off flares in Bolotnaya Square.
Public figures like detective writer Boris Akunin and journalists Leonid Parfenov and Oleg Kashin are getting more cheers from the crowd than opposition parties representatives, says Alexei Belovs, who is monitoring live feeds of the protest. Parfenov criticized the media and described current television broadcasting as "obscenity with badminton".
Russian rapper Noize MC has addressed the crowds and demanded re-elections.
Here's a video report by Russia Today about the protest.
Around 2,000 people have gathered at a protest in the city of Penza, 625km (388 miles) south east of Moscow.
Russian media reports that local government officials offered people free zoo tickets and guided tours of the city in a bid to deter them from attending the rally.
One person has been arrested at the demonstration in Saint Petersburg, the independent Ridus news website reports [in Russian].
My colleague Alexei Belovs says mobile internet access has now been cut off in Bolotnaya Square.
My colleague Miriam Elder who is in Bolotnaya Square has just called to say the crowd is now so huge that it is overspilling onto the bridges that lead onto the island.
The crowd is so huge. I've never seen anything like it in Moscow. The entire square is filled. On one of the bridges leading to the island someone has hung a banner that says "Crooks and thieves return the elections" [ – a reference to Putin's United Russia party].People are shouting "Freedom", and "Clean elections". It's mostly a young, middle class crowd, though there are a few hardcore nationalists.
A Russian woman holds an anti-Putin placard. Photograph: Yuri Kadobnov/AFP/Getty Images
She spoke to one woman who told her she'd travelled an hour by bus to attend the protest. The woman said she had never voted before the disputed election.
The square is festooned with white ribbons and white flowers – symbols of the protest movement.
Moscow Police now say around 25,000 people have gathered at Bolotnaya Square.
The Russian authorities appear to be restricting internet access at the Moscow demonstration. Wifi access has been shut down, though there is still some mobile internet service.
Revolution Square is now empty with all protesters now either at or en route to Bolotnaya Square.
Protesters mass in Bolotnaya Square in central Moscow. Photograph: Yuri Kadobnov/AFP/Getty Images
At Bolotnaya, Russian news anchor Leonid Parfyonov has warned the crowd about the increasing control of the media by the state.
The Moscow Times has tweeted what seems to be an attempt by police to deter protesters from joining the Moscow rally.
It says: "@rianru reports police are warning the footbridge to Bolotnaya could collapse."
Moscow Police says there are 15,000 protesters now gathered at Bolotnaya Square, although demonstrators and the media say the number is higher.
The Moscow Times tweets: "An absolute sea of people cramming Bolotnaya Ploshchad. Difficult to count numbers. @Vedomosti claims 30,000. Its believable."
Among those to address the crowd is Boris Akunin, a renowned Russian novelist, who is proposing fresh elections with a live video feed from every polling station to prevent fraud.
The #10dec tag on Twitter is being flooded with provocative and misleading messages, writes Alexei Belovs.
Among the false messages being put out are "I have seen people with syringes, be careful everyone!" and "If you wear a white ribbon you support gay self-murderers".
Alexei is monitoring the Russian media for us today. You can contact him on Twitter @purpl_oranj or email him at alexei.belovs@guardian.co.uk.
The protesters marching from Revolution Square to Bolotnaya Square, chanting "Putin is a thief" and "Jail Churov" – referring to Vladimir Churov, the chairman of the Central Election Commission of Russia.
Miriam Elder has posted a Twitpic of people marching past St Basil's cathedral.
You can find a map of all today's protests against the disputed Russian elections here.
Thousands are now marching from Revolution square to Bolotnaya Square, tweets Miriam Elder.
She says the police, who are out in force, appear to be in shock at the scale of the demonstration but so far the scene remains peaceful.
Opposition leader Eduard Limonov addresses the crowds. Photograph: Grigory Dukor/REUTERS
One of Putin's fiercest critics Eduard Limonov is addressing the crowds at the Revolution Square.
US NBC News correspondent Stephanie Gosk tweets: "Moscow there are already so many protesters they have filled the approved location. Police no longer letting them in the square."
You can follow live-streaming video of the Moscow protest here.
The Guardian's Moscow correspondent Miriam Elder, who is covering today's protest, says human rights activists Oleg Orlov and Lev Ponomaryov are directing protesters to Bolotnaya square.
Here's a photo she took at the scene. You can follow Miriam on Twitter @MiriamElder.
Here's a link to a video she posted earlier of hundred of people joining the march.
Yevgenia Chirikova, an environmental activist turned opposition leader, has also made an appearance at Revolution square. Earlier this week she expressed fears that the Russian authorities would step up their action against protesters.
Moscow's Red Square is blocked by military vehicles as you can see in this photo. Dozens of trucks with riot police line the streets.
Storyful has also collated photos of troops deployed in the capital and videos of earlier demonstrations.
Protests have already taken place in cities in Siberia and the far east of Russia.
In Vladivostok, where Putin's party was beaten by the communists, police looked on about 1,000 protesters called for the election to be annulled and detained activists freed, Reuters reports. Here's a video of the protest and a link to another video of a protester addressing the rally.
A rally was held at a port where some of Russia's Pacific Fleet warships are docked, AP reports. Protesters shouted "Putin's a louse" and some held a banner caricaturing United Russia's emblem, reading "The rats must go." Police stayed on the fringes of the demonstration and made no arrests.
The Interfax news agency reported that an unsanctioned flash-mob protest in the Far Eastern city of Khabarovsk was broken up by police, who arrested about half the 60 participants. Some of the protesters had their mouths sealed with tape.
Our Moscow bureau has sent through more information on the number of protesters in the regions.
Around 4,000 people gathered in Novosibirsk, Russia's third largest city and the largest city in Siberia.
Elsewhere in Siberia about 1,000 people attended a rally in Barnaul, around 700 gathered in Krasnoyarsk, 200 gathered in Chita and about the same number protested in Ulan-Ude.
Good morning and welcome to our coverage of today's mass protests against the disputed Russian parliamentary elections. This is David Batty – you can follow me on Twitter @David_Batty.
Tens of thousands of Russians are expected to rally in Moscow in the biggest show of opposition yet to Vladimir Putin's strongman rule since he came to power 12 years ago. More than 35,000 demonstrators indicated via Facebook that they planned to join the protest in Bolotnaya (Swamp) Square, on a large island in the Moskva River. More than 50,000 police and 2,000 interior troops, backed by water cannon, helicopters and reinforced arrest lorries, have been deployed in the city.
Protests are planned for more than 80 Russian cities, in what is likely to prove the largest public show of discontent in the post-Soviet age. In St Petersburg 12,000 have indicated their intention to take part via VKontakte, a Russian social networking site.
Protests attracting between several hundred to more than 1,000 people have already taken place in cities in Siberia and the Far East. A demonstration is also planned in central London.
The opposition are demanding the annulment of the parliamentary elections on December 4, which were marred by fraud, and the holding of new elections.
Opposition groups have been bolstered by the sense that the elections showed Putin and his United Russia party to be vulnerable. The party held an overwhelming two-thirds of the seats in the previous parliament, but its share plunged by around 20% in the recent vote. Protesters say that even its reduced performance was inflated by ballot-box rigging.