With around 20% of the vote counted, the Kremlin-backed Dmitry Medvedev was reported by Russia's Central Election Commission to have garnered some 65% of the vote. This would be enough to give him victory in the first round of voting. Some exit polls gave Medvedev 70%.
The Central Election Commission said Communist party leader Gennady Zyuganov had received 19.73%, nationalist Vladimir Zhirinovsky - 12.47% and the leader of the tiny, pro-Western Democratic Party, Andrey Bogdanov - 1.53%.
The Communist Party complained of the mass infringement of voting procedures, with the secretary of the party's central committee, Valery Rashkin, speaking to journalists of "impudence" on behalf of the authorities.
"We've never seen this sort of impudence before. This is a new era," he said.
He added that the Communist party had noted voting violations in many Russian cities, including Saint Petersburg.
The leader of the ultranationalist Liberal Democratic Party also spoke of his intention to argue the results of the poll in court.
Answering a question from journalists as to whether he would go to court over the results of Sunday's polls, Zhirinovsky replied, "We've always gone to court - without result. We'll go to court this time as well."
"The best indication of how Russia voted will be clear tomorrow...All Russia's 109 million citizens [eligible voters] will go to work tomorrow with gloomy faces. Everyone voted with gloomy faces today. There wasn't a smile to be seen," he added.
The Russian Central Election Commission said, however, that the polls had taken place without serious violations.
Many Western observers, including the OSCE's main election arm, chose to boycott the election over restrictions imposed by Russia. Moscow rejected claims that it had imposed restrictions on monitors however.
President Putin publicly backed Dmitry Medvedev and said that he would take up Medvedev's offer to become Russia's prime minister if his ally won the election. Putin was barred from standing for a third term by Russia's Constitution.