Vladimir Putin has declared victory in Russia's presidential elections at a mass rally outside the Kremlin walls, telling his voters they helped avert attempts to break up the Russian state.

Mr Putin and outgoing Kremlin chief Dmitry Medvedev walked out side by side before a throng of more than 100,000 supporters outside the Kremlin following the release of early results that showed him winning more than 60% of the vote.

"We won today...thanks to the overwhelming support of the overwhelming majority of our voters. We have won in an open and honest battle," said Mr Putin.

"I promised you that we will win. And we won. Glory to Russia!" he shouted as the crowd cheered back in unison.

State-run VTsIOM polling institute projected that Mr Putin would win 58.3% of the vote.

Early results based on 14.5% of Russia's polling stations said he had won 61.8% of the vote, the central election commission said.

The early results, gathered mainly from the Far East and Siberia where polls closed several hours earlier, showed Communist Party leader Gennady Zyuganov trailing in second with 17.8%.

Firebrand nationalist Vladimir Zhirinovsky was scoring 8%, tycoon Mikhail Prokhorov had 7.6% of the vote, while former upper house speaker Sergei Mironov was fifth with 3.7%, early results showed.

VTsIOM, whose exit polls are commissioned by Russian state television and which has developed a reputation for closely predicting final results, said 31.7% of the respondents refused to answer their survey.

Critics have questioned the legitimacy of today’s vote, which they say, is skewed to help the former KGB spy return to the Kremlin after four years as prime minister.