Russian demonstrators clashed with riot police Monday, leading to the arrests of hundreds following a rally protesting president-elect Vladimir Putin's victory as fraudulent.

Several opposition leaders were arrested and journalists reportedly beaten during scuffles with police in riot gear, GRN's Jessica Gollogher told CBC News from Moscow.

What began as a peaceful demonstration that drew about 20,000 angry citizens to downtown Moscow reportedly turned violent for several hundred.

"[Protesters] were roughed up," said Gollogher, who attended a mass rally on Pushkin Square, about a kilometre away from the Kremlin. "I talked to many colleagues, who say they saw many protesters being dragged away in police vans."

The head of the Central Election Committee Vladimir Churov, second left, announces the results of presidential elections during a news conference in Moscow, Monday. Vladimir Putin scored a decisive victory in Russia's presidential election Sunday to return to the Kremlin and extend his hold on power for six more years. (Sergey Ponomarev/Associated Press)

Gollogher said the tide turned when police moved in to force the dispersal of the crowds when the rally was expected to wind down. Organizers had urged protesters to continue occupying the square until Putin agreed to cede power.

"Police didn't think that people were moving quick enough, and some people were arrested after the rally was over," Gollogher said.

The atmosphere was tense to begin with, as dozens of trucks waited in several areas downtown. Scores of helmeted police wielding riot shields stood guard.

Outspoken blogger and opposition leader Alexey Navalny, who has emerged as a leading anti-government voice, was among those arrested, CBC's Alex Shprintsen reported from Moscow.

Crowds chant for 'Russia without Putin'

Protesters had earlier called for an encore speech from Navalny, after he delivered a fiery condemnation of the Putin regime to the crowd.

Demonstrators contesting the legitimacy of Sunday's vote chanted "Shame!" and "Russia without Putin!"

According to the nearly complete official returns, Putin took more than 63 per cent of the vote, but opposition leaders believe it wasn't a free and fair election — a sentiment shared by some international observers.

P.O.V. Was Putin's win legitimate? Take our survey.

The U.S. expressed concern over the outcome and called for "an independent, credible investigation" of the fraud allegations on Monday.

France joined the chorus of condemnation, though it pledged to continue its partnership with Russia and other European countries. French Foreign Minister Alain Juppé summarized his assessment of the outcome sharply, telling a news conference: "The election has not been exemplary. That is the least you can say."

In Ottawa, a statement issued from Foreign Affairs Minister John Baird's office acknowledged the charges of voting fraud and said the department would continue to work for democracy around the world.

"We note with concern the identification of 'procedural irregularities' that tainted the vote count in nearly one third of polling stations," the statement said.

Independent election monitors noted the campaign was heavily slanted in Putin's favour and said the vote count "was assessed negatively" in almost a third of polling stations observers visited.

"The campaign has been unfair, cowardly and treacherous," said opposition leader Grigory Yavlinsky, who had been denied registration for the race on a technicality.

Vote closer to 50%, says watchdog

Police quickly rounded up Eduard Limonov, the leader of the banned National Bolshevik Party and several dozen of his supporters, who attempted to hold an unsanctioned protest near the headquarters of Russia's main security agency.

Opposition leader Alexey Navalny, who addressed a crowd of protesters Monday, was arrested during a demonstration challenging Vladimir Putin's election victory. (Alex Shprintsen/CBC)

About 100 protesters were also arrested in St. Petersburg, where about 2,000 gathered for an unauthorized rally.

The independent Russian elections watchdog Golos said Monday that incomplete reports from its observers of individual polling station counts contradicted the official vote count, indicating that Putin hovered perilously close to the 50 per cent mark needed for a first-round victory.

"It's one pixel away from a second round," said Golos's Roman Udot.

Putin's win was assured as he faced a weak slate of Kremlin-approved candidates and many across the vast country still see him as a guarantor of stability and the defender of a strong Russia against a hostile world, an image he has carefully cultivated during 12 years in power. He has denounced his foes as Western stooges working to weaken Russia.