Russian activists detained after protests over results of criticized election which kept Putin’s United Russia in power.

Hundreds of Russian opposition supporters are being held by police following overnight protests in Moscow against the results of Sunday’s parliamentary elections.

About 250 people were detained on Tuesday morning and face being held for up to 15 days, said Olga Shorina, a spokeswoman for the Solidarnost (Solidarity) activist group that organized the protest.

Several thousand people took to the streets in central Moscow late on Monday to protest against alleged fraud and voting irregularities after Vladimir Putin’s United Russia retained power, albeit with a greatly reduced share of the vote.

Police said they had arrested 300 people including Ilya Yashin, a prominent activist, and Alexei Navalny, an opposition blogger, after the protesters marched towards Lubyanka Square where the headquarters of Russia’s FSB security service is located.

Al Jazeera’s Neave Barker, reporting from the rally, said police locked down the centre of the city after several hours of violent clashes between anti-government protesters and riot police backed by interior ministry forces.

He said protesters had gathered to listen to opposition leaders but many demonstrators ended up clashing with police who had hemmed in rally participants.

‘Russia without Putin’

During the rally, organized mostly through online social networks, protesters chanted “Russia without Putin” and “Putin should be in prison.”

Navalny has won a huge online following 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, the lower house of the Russian parliament, was sharply reduced.

United Russia obtained 238 seats in the 450-seat Duma, 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 percent in 2007.

The opposition claimed the results would have been even more dramatic in clean elections.

‘Procedual violations’

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 mobilize protesters in a country which 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.