International election observers have called for an investigation into Sunday's Russian presidential polls. The OSCE says the campaign favored Putin.
International election monitors say Sunday's presidential vote in Russia was not a fair contest.
"There was no real competition, and abuse of government resources ensured that the ultimate winner of the election was never in doubt," Tonino Picula of the Organization for Security and Cooperation in Europe (OSCE) told reporters in Moscow on Monday.
"The point of elections is that the outcome should be uncertain. This was not the case in Russia," Picula said.
The observers also called for all alleged electoral violations to be thoroughly investigated.
The OSCE press conference came just hours after Russia's central election commission had officially declared that Putin had won the election.
"According to the preliminary results, Vladimir Vladimirovich Putin has been elected president of the Russian Federation," the head of the election commission, Vladimir Churov, told reporters in Moscow.
With more than 99 percent of the votes counted, Prime Minister Putin had 63.75 percent of the votes. His closest rival was the head of the Communist Party, Gennady Zyuganov, who won 17.19 percent.
"As you can see, there will be no second round," Churov added, referring to the fact that Putin had taken well over the 50 percent needed to win the election outright.
Putin had already claimed victory Sunday night, in an address to thousands of supporters near the Kremlin.
"I have promised that we would win and we have won," he said. "We have won in an open and honest struggle."
More than 3,000 irregularities reported
The opposition though claim Putin won his landslide at least in part due to widespread fraud in the election. There have been numerous reports of "carousel voting," in which people voted at several different polling stations. Security camera footage also appeared to show people feeding numerous ballots into automated counting machines.
The elections watchdog organization Golos said it had received reports of more than 3,000 irregularities.
Meanwhile, security was stepped up in Moscow on Monday ahead of a rally that Russia's opposition movement said would bring tens of thousands of demonstrators out on the streets to protest against Vladimir Putin's landslide victory in Sunday's presidential election.
An extra 6,000 police officers are reported to have been sent to the capital ahead of the rally, which has been sanctioned by the authorities.
pfd/ncy (AP, dpa, Reuters)