Thousands protest Putin's victory at Moscow rally

Thousands of Russians are gathering for a massive rally to challenge Prime Minister Vladimir Putin's victory in Russia's presidential election.

Putin won more than 63 percent of Sunday's vote according to the nearly complete official returns, but the opposition and independent observers say the election has been marred by widespread fraud.

International election monitors pointed at the lack of real competition in the race and said the vote count "was assessed negatively" in almost a third of polling stations observers visited.

The criticism of the vote added fuel to Monday's protest in downtown Moscow by Putin's foes who are questioning his victory and demanding an end to his 12-year rule. The rally, which follows a series of massive previous protests against Putin's rule, has been sanctioned by authorities.