Thousands of cars filled Moscow's ring road Sunday in a protest demanding free elections and slamming Prime Minister Vladimir Putin's bid to regain his Kremlin job in March polls.

Some 3,000 cars decked with white ribbons and balloons -- the color of the anti-Putin movement -- joined the protest, according to organizers, while police said they numbered only 300.

The office of a Russian regional newspaper published by the Yabloko opposition party has been destroyed in a Molotov cocktail attack, the party said on Sunday.

The attack on the Vecherny Krasnokamsk weekly in the Perm region in the Urals occurred early Saturday, Yabloko said on its website. No one was reported hurt in the pre-dawn incident.

Around 15,000 people Saturday thronged a city in the Russian Urals in rally organized by labor groups to show mass working class support for Vladimir Putin's bid for a new Kremlin term, police said.

The rally in Yekaterinburg appeared to be a move by the authorities and trade unions to show Putin retains broad workers' support after the mass protests against his rule mainly attended by the Moscow middle class.

Russia on Friday disqualified Vladimir Putin's liberal challenger Grigory Yavlinsky from the March 4 presidential ballot, in a move slammed by his supporters as undermining the legitimacy of the polls.

Russia's central elections commission said it could not accept nearly a quarter of the registration signatures gathered by Yavlinsky's Yabloko (Apple) party because they were either photocopies of originals or fakes.

Russia will never become a dictatorship, Russian Prime Minister Vladimir Putin said Wednesday, as he continued his bid for a third term as president despite unprecedented protests against his rule.

"We have an open country and no matter what they say or write, no matter what scary statements they make about some sort of dictatorship, we don't have that and -- I hope -- never will," he told students of Tomsk Polytechnic University in Siberia.

Russia needs real political change, not a "survival mechanism" for the current regime, a Council of Europe Parliamentary Assembly delegation said Saturday.

The group, which observed last month's controversial parliamentary elections, was speaking in Moscow ahead of the presentation of its final report at a plenary session in Strasbourg on Monday.

Russian President Dmitry Medvedev on Monday submitted a bill to parliament that would reinstate the direct election of regional governors following mass protests calling for reform.

Under the bill, Russian citizens would elect their regional leaders running independently or on a party ticket for a term of five years, the Kremlin said in a statement.

A leader of Russia's liberal opposition was arrested Saturday at a protest rally against fraud-tainted parliamentary polls as Vladimir Putin seeks a third Kremlin term in the face of attacks on his 12-year rule.

Sergei Mitrokhin, a leader of the Yabloko party which called the rally, was arrested at the end of the protest attended by some 300 people and was now facing a fine or a 15-day jail term, a party spokesman told Agence France Presse.

Prime Minister Vladimir Putin on Thursday vowed to end police repression in Russia and make government accountable, as he kicked off his campaign for presidential elections after mass protests.

In his manifesto for the March 2012 elections where he plans to take an unprecedented third Kremlin term, Putin also promised to build a strong Russia and retaliate against Western states that failed to listen to Moscow.

Russian riot police arrested dozens of people on Saturday in Moscow and Saint Petersburg who tried to stage unsanctioned New Year's Eve protests against 12 years of Vladimir Putin's dominant rule.

The show of police force marked the first time the authorities had cracked down on members of the Russian opposition since allowing two massive rallies on December 10 and December 24.