MOSCOW — Thousands protested Russia's ruling regime in central Moscow on Saturday calling for transparent elections as the pro-Kremlin Nashi movement staged a massive anti-corruption demonstration.

Up to 3,000 people protested on Moscow's Bolotnaya square near the Kremlin in a protest organised by the unregistered oppositional Party for People's Freedom, an AFP correspondent estimated.

Moscow police estimated the turnout at 900 people. People chanted "Russia Without Putin" and other slogans, waving banners reading "Let's Take Back the Right to Choose".

The two-hour protest was preceded by a large demonstration in another part of central Moscow staged by the pro-Kremlin Nashi movement.

Nashi said in a statement that 50,000 young people from 20 Russian cities "demanded answers to inconvenient questions about corruption" in personal videos, which were then shown on a big screen at the demonstration.

Witnesses estimated the actual turnout at no more than 30,000.

Young people brought to Moscow in dozens of buses waved flags and rocked to techno beats interspersed with soundbites on corruption by Prime Minister Vladimir Putin, an AFP correspondent said.

"Corruption is not normal. It should not exist in our country," said one girl, sporting dreadlocks and identifying herself as Yelena from St. Petersburg.

Some people wore pig and rat costumes, and several flags said "Piggies Are Opposed!" However no written banners were observed, and the aprons worn by the activists had random messages written on them such as "Misha, call me".

A central Moscow street was blocked off for two days for the Nashi protest, something rare even in the Soviet era when state demonstrations were a routine occurrence on major holidays.

Opposition politician Boris Nemtsov, one of the founders of the Party for People's Freedom, earlier said that the Nashi demonstration was hastily organised due to the authorities' concern about his opposition protest.

Corruption has become a cause celebre in Russia for both the opposition and some government officials, including President Dmitry Medvedev who made it one of the frontline issues of his presidency.

Influential Kremlin advisor Vladislav Surkov met with Nashi on Wednesday advising them to address corruption and accusing the opposition of "living on grey foreign grants," Russian agencies reported.