MOSCOW - Thousands of Russians gathered here Saturday to protest against alleged vote fraud in the State Duma elections.

Protestors hold placards and balloons during a demonstration against recent parliamentary election results in Moscow Dec 24, 2011. Thousands of people gathered in Moscow on Saturday to call for a disputed election to be rerun, increasing pressure on Vladimir Putin as he seeks a new term as Russian president. [Photo/Agencies]

According to the rally organizers, up to 50,000 people are expected to attend the protest on Sakharov Avenue in downtown Moscow, which has been specially cut off to traffic for the gathering.

The city police said tough security measures had been taken and protestors had to pass some 50 metal detectors to enter the avenue.

The rally organizers have promised the demonstration, under the slogan "For Fair Elections," would be safe and calm.

Former Russian Finance Minister Alexei Kudrin, who resigned in September amid a spat with President Dmitry Medvedev over government budget policy, had arrived at the rally, according to Interfax news agency.

Local media reported billionaire Mikhail Prokhorov, who plans to run against Vladimir Putin in the March 2012 presidential elections, would also take part in the protest.

There were large screens, loudspeaker equipment and field kitchens at the venue. About 4 million roubles had been collected through social networks to finance the rally, local media said.

This is the second mass protest this month. On December 10, more than 40,000 attended a rally at Bolotnaya Square, across the Moskow River from the Kremlin, demanding honest elections and a vote recount.