Moscow police were on Tuesday holding several Russian opposition figures after breaking up an unprecedented protest against polls monitors said were slanted in favour of Vladimir Putin's ruling party.

Several thousand people took to the streets in central Moscow late Monday despite pouring rain for a rally against the results of Sunday's elections in which Putin's United Russia party won but with a sharply reduced majority.

Police said they arrested 300 people including prominent activist Ilya Yashin and opposition blogger Alexei Navalny after the protesters marched towards the Lubyanka Square that houses the feared FSB security service.

Around 250 were remained detained by Tuesday morning, Olga Shorina, spokeswoman for Solidarnost (Solidarity) movement that organised the protest, told AFP. Many now face 15 days of arrest, she said.

During the rally -- called mostly through social networks whose use has boomed in Russia in recent years -- protesters chanted 'Russia without Putin' and 'Putin should be in prison'.

Navalny has won a huge following on the Internet for exposing corruption at state-owned firms and he coined the phrase, which has now been taken up by all the opposition, 'swindlers and thieves' to describe United Russia.

Putin suffered his worst ever setback at the ballot box on Sunday as United Russia's majority in the State Duma was sharply reduced. The opposition claimed the results would have been even more dramatic in clean elections.

Monitors led by the OSCE said the polls were slanted in favour of United Russia and marred by 'frequent procedural violations' including ballot stuffing. US Secretary of State Hillary Clinton raised 'serious concerns'.

Along with United Russia, three other usually pliant opposition parties won seats in the State Duma, including the Communists.

However liberal party Yabloko failed to win sufficient votes for seats and another anti-Kremlin force, the Parnas party, was not even registered for the vote.

According to police, 2,000 people showed up at the Moscow rally while Shorina said up to 10,000 attended the rally and 1,500-2,000 marched later towards the offices of the Central Election Commission.

It was the largest protest in many years and a boost for Russia's embattled opposition which traditionally struggles to mobilise protests in a country which has lost its taste for street politics in the turbulent 90s.

Police said about 100 opposition protesters were also detained in Russia's second city of Saint Petersburg after they tried holding an unsanctioned rally on the main Nevsky Prospekt thoroughfare on Monday for the second day in a row.

United Russia obtained 238 seats in the 450-seat State Duma in Sunday's polls, down sharply from the 315 seats it won in the last polls in 2007.

Its biggest opposition will be the Communist Party with 92 seats. It was followed by the A Just Russia party with 64 seats and the ultra-nationalist Liberal Democratic Party with 56 mandates. Turnout was just over 60 percent.

The United Russia only managed to win 49.35 percent of the vote, down sharply from over 64 per cent in 2007. This was the first time that Putin or his party had endured a decline in support in an election.

The opposition said that the authorities had used unprecedented dirty tricks to keep United Russia's dominance in the State Duma despite falling support.

A string of news websites that show sympathy for the opposition were paralysed on election day, including Moscow Echo radio, the Kommersant newspaper and The New Times magazine in an apparent mass cyber attack.

The website of the independent monitor group Golos, which exposed a string of violations in the campaign, was also down after a week of harassing of its leaders by the authorities.

While in some regions United Russia barely received over 30 percent of the vote, it saw credibility-busting shows of support in the mainly Muslim regions of the Northern Caucasus including 99.50 per cent of votes in Chechnya.