Demonstrators carried white balloons and wore white ribbons, the symbols of protests that began over a disputed parliamentary poll on December 4 and are intended now to highlight allegations of fraud in the presidential election Putin won on March 4.

Putin's opponents hoped to attract a large crowd to maintain the momentum of the rallies, which could quickly fade following Putin's triumph and the detention of hundreds of people during or after protests on Monday.

Early signs were that the protest would be smaller than the largest protests that have attracted tens of thousands of people over the past three months.

The mood was relaxed on a cold but sunny day on Moscow's Novy Arbat street at a rally approved by the city authorities. Police were out in force and two helicopters hovered overhead.

Protests leaders addressed the crowd from a stage bearing the slogans "For new elections" and "These are not elections, this is not a president".

"These authorities are illegitimate," Vladimir Ryzhkov, a opposition leader and protest organiser, told the crowd.

"The same people are in power: The same people who took away our right to choose, the same people who destroyed freedom of speech and political competition," he said.

"We will continue to demand deep political reforms and new elections. We will continue to demand they free all political prisoners...We will continue to demand freedom of speech and the media."

Liberal opposition leader Grigory Yavlinsky, who was barred from running in the presidential election, told reporters that people should be patient as they seek to change the political system which is dominated by Putin.

"If this system took 15 or so years to be created, we need a few years - three, four, five - to dismantle it. Of course we will need it. That's why we need these demonstrations," he said.

International election monitors say the presidential election was clearly skewed in Putin's favour but the Central Election Commission said there were no serious violations.

The protest organisers say there were many examples of cheating, and that Putin probably won far fewer votes than the official tally of more than 63 percent. They refuse to recognise the official results.

Copyright Reuters, 2012