'Glory to Russia!'

Organisers of Monday's rally in Moscow said on Facebook: "We consider the presidential election not free and not legitimate.

"It was run by the same electoral commission which stole our votes on 4 December [at the parliamentary election]."

Alexei Pushkov, an adviser to Mr Putin, told the BBC that while there might have been violations, they had happened on all sides, and would not have distorted the final result.

Speaking to tens of thousands of supporters in Moscow on Sunday night, an emotional Mr Putin said he had won in an open and honest battle.

"I promised you we would win, and we won - glory to Russia!" he said.

Mr Putin moved into the post of prime minister in 2008 because of a constitutional ban on a third consecutive term as president.

He will return to the presidency in May - replacing his close ally Dmitry Medvedev - and remain in post until 2018, when he could then run for another six-year term.

2 Can online gaming influence a us presidential election?

First came Farmville. Then came FourSquare. But can games played online actually shape an election?

Political games have been around as long as politics. But advances in technology and social media could make them a huge factor in the upcoming US presidential election.

Gamification sounds like the latest in high-tech digital campaigning. In fact it's a centuries-old strategy taking on new life in the age of social media.

"Gamification is taking the rules of games - whether it's levelling, prizes [or] achievements - and the psychology of playing games and applying it to something that doesn't have that dynamic," says Peter Corbett, CEO of iStrategiesLab, a Washington DC-based interactive firm.

Consider FourSquare - the social media app asks users to "check in" at their current location using geotagging software. Users are rewarded points for each check-in, earn 'badges' for frequenting certain types of places (the JetSetter badge, for instance, is earned after checking into multiple airports), and compete against their friends to see who can rack up the most points each week.

In exchange, businesses lure patrons with FourSquare-specific specials and use FourSquare's data to learn about their customer base.

In the same way that FourSquare makes buying a cup of coffee a competitive event, political operatives are trying to harness the power of games to collect data and engage potential voters.

'Changed behaviour'

"What's happened over the last few years is that politicians, political parties, non-profits, and lobbyists have realised that games can be used to influence voter behaviour," says Gabriel Zichermann, the CEO of Gamification Co.

"Games are the best forum of behaviour modification therapy than we have," he says, adding that behaviour change has always been a huge part of politicking.

"It's always about influencing decision-making, and about engaging people to take a certain action: campaign, recruit your friends, vote for our candidate."

Digital advertising firm Engage is currently experimenting with online gamification for some of their political clients. They were part of the team that developed the "I Voted" badge on FourSquare, designed to increase awareness of election day and encourage voter turnout.

They also offer a social media platform, called Multiply, that integrates gamification techniques into a candidates' website. Visitors to the website of House Speaker John Boehner, for instance, can earn badges for checking in from the speaker's home state of Ohio, or by linking the page to their Facebook account.

"The user gets instant gratification, a sense of involvement and participation and gratitude," says Patrick Ruffini, the president of Engage. "The campaign gets data."

That data helps the candidate better organise and target potential voters, donors and volunteers.