Moscow (CNN) -- Russian President Dmitry Medvedev has called for a probe into allegations of vote fraud in recent parliamentary elections, according to a post on his Facebook page Sunday.
The announcement came a day after thousands of protesters braved freezing temperatures to demonstrate in several cities to protest what they believe were rigged elections.
"I agree neither with the slogans nor the statements voiced at the protests," the statement on Medvedev's Facebook page said. "Nevertheless, I have ordered checks into all the reports from polling stations, regarding the compliance with the election laws."
United Russia, the party of Prime Minister Vladimir Putin, suffered big losses in the election, but retained its parliamentary majority, according to official results.
On Saturday, protesters in Moscow claimed the results were fraudulent and chanted "Putin out," according to the state-run RIA Novosti news agency.
About 25,000 protesters demonstrated in a central square Saturday, RIA Novosti said, citing police. There were no arrests, RIA Novosti reported.
Organizers said 40,000 people had massed, the news agency reported.
The protesters demanded an annulment of the December 4 election and a new vote.
Around 7,000 people rallied in St. Petersburg, Russia's second largest city, RIA Novosti said, citing police.
Hundreds of protesters were arrested during demonstrations last week. Police said they cracked down on those demonstrations because the turnouts were not legal and the protesters were being disorderly.
Election officials on Friday released the official election results: 238 seats for United Russia; 92 seats for the Communists; 64 seats for Fair Russia; and 56 seats for the Liberal Democrats.
Arkady Irshenko and Phil Black contributed to this report.