MOSCOW -- Russian opposition leader Boris Nemtsov was among hundreds of people arrested at a protest in central Moscow on the second consecutive night of public anger over parliamentary elections marred by widespread accusations of fraud.
News agencies quoting police sources said more than 400 people were arrested in the capital. Around 200 people who tried to hold an unsanctioned rally were arrested in St. Petersburg. Another 25 protesters are said to have been detained at a protest in Rostov-na-Donu.
Among those arrested were the head of the Memorial human rights group Oleg Orlov, Yabloko leader Sergei Mitrokhin, former Deputy Prime Minister Boris Nemtsov, and Eduard Limonov, head of the unregistered Other Russia party.
Gazeta.ru reported that several journalists were also detained. Kommersant FM radio posted on Twitter that one of its reporters was detained, beaten up, and had his phone smashed by riot police.
Opposition protesters called for the police to stand with them and against the establishment, which they called "the monsters."
The rally in the capital took place despite a heavy police presence aimed at preventing a repeat of December 5, when more than 5,000 protesters took to the streets to express their opposition to Prime Minister Vladimir Putin and his United Russia party, which claimed a majority of seats in the December 4 parliamentary elections.
Local and international election observers reported widespread ballot stuffing and irregularities in the vote count.
Hundreds of riot police in helmets and armed with batons forcibly drove protesters from the city's Triumph Square. Scuffles with police ensued and protesters were dragged into waiting police trucks.
Viktor, a 57-year-old businessman who was taking part in the opposition protest, said the "fraudulent" election had motivated people like him to take their complaints to the streets.
"The situation in the country reminds me of what it was like in the early '90s," he said.
READ MORE: Vote violations alleged across Russia
The seriousness with which the Kremlin is taking the challenge to its authority was evident in rival, officially sanctioned demonstrations that took place throughout the day.
One pro-government youth rally featured hundreds of Young Guard activists trying to drown out the opposition by beating on drums and chanting, "Down with the fascists!"
The teen-heavy crowd chanted "Russia! Putin!" and waved United Russia banners and teddy bears, symbolic of the party.
Across the street, opposition protesters chanted, "Russia without Putin!'
At a United Russia rally called "A Clean Victory," party member and Duma deputy Svetlana Zhurova said she is looking to the future.
"The opposition is now looking for ways to discredit us, saying bad things about us," she said. "But we have come here today not to talk about falsification but about our plans. We are saying we will fulfill all the promises that we have made. We are saying we have and will do what United Russia planned in its program. We know that the future is with us."
The international community is continuing its criticism of Russia over the conduct of the parliamentary vote.
Speaking in Vilnius to foreign ministers of the election-monitoring Organization for Security and Cooperation in Europe, U.S. Secretary of State Hillary Clinton repeated criticism of Russia's weekend elections, saying they leave room for "serious concerns."
Clinton said she was also concerned by reports that independent Russian election observers, including the nationwide Golos network, were harassed.
The European Union's foreign policy chief, Catherine Ashton, took note of the fact that the Duma election was well-prepared and administered, adding: "Reports of procedural violations, such as lack of media impartiality, lack of separation between party and state, and the harassments of independent monitoring attempts are, however, of serious concern."
Russian President Dmitry Medvedev rejected the international criticism as amounting to interference in Russia's affairs.
The Foreign Ministry in Moscow dismissed U.S. criticism in particular as "unacceptable."