The Russian election was "clearly skewed" in favour of Vladimir Putin, according to the independent Organisation for Security and Co-operation.
Tonino Picula, the special co-ordinator to lead the short-term observer mission said there were "serious problems" and "irregularities" in the election.
The Organisation for Security and Co-operation (OSCE) is one of the world’s largest regional security organisation with 56 states from across the globe as members.
Picula said: "There were serious problems from the very start of this election. The point of elections is that the outcome should be uncertain. This was not the case in Russia. There was no real competition and abuse of government resources ensured that the ultimate winner of the election was never in doubt."
In a statement the OSCE said Putin had a "clear advantage" over his competitors in terms of media presence.
Heidi Tagliavini, the head of the election observation mission of the OSCE Office for democratic institutions said candidates were unable to compete "on an equal footing."
The conference comes amid widespread allegations of fraud following Putin's victory in the Russian presidential elections on Sunday night.
According to Tiny Kox, the head of the delegation of Council of Europe’s Parliamentary Assembly, voter's choice was "limited."
Opposition figures said they were preparing huge demonstrations against the result in Moscow on Monday.
With 99% of ballots counted the United Russia leader won with almost 64% of the vote, election officials said.
"I promised you we would win, and we won," Putin shouted to a flag-waving crowd of thousands of supporters outside the Kremlin on Sunday night, after claiming victory with just a quarter of votes counted.
Julia Pettengill, a research fellow at the Henry Jackson society said opposition could force Putin to leave office before his term ends in 2018.
"The opposition movement represents the greatest challenge to Putin's legitimacy since he came to power in 2000. Putin faces a broad-based, non-ideological protest movement which has gained strength in successive protests to become the most significant anti-government movement since the collapse of the Soviet Union.
"The Russian public no longer enjoy the levels of economic growth which once made the bargain of the Kremlin's so-called 'sovereign democracy'-restricted political liberties exchanged for economic prosperity-tolerable. (GDP growth is expected to diminish to 3.5% in 2012)."
Downing Street has said prime minister David Cameron is to call Vladimir Putin later on Monday but would not be drawn on whether he would congratulate the president on his election victory.
"It is clear that the election has delivered a decisive result," the prime minister's spokesperson said on Monday.
"Even the NGO polling data put Putin above the 50% needed to win in the first round. It is right that these assessments have taken place. They have clearly identified some problems. We would like to see these issues addressed over time."
Shadow foreign secretary Douglas Alexander MP said there were "real questions" about the election. “The Russian authorities should be in no doubt that the world will be watching their actions closely in the coming hours and days.”
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