Thousands of people have held rallies across Russia protesting against what they describe as the government's mismanagement of the economy.
The biggest demonstration took place in the eastern city of Vladivostok, where protesters demanded the resignation of Prime Minister Vladimir Putin.
In the capital Moscow, police arrested a number of people at an unauthorised gathering by a radical party.
Meanwhile, government supporters also held their rallies across the country.
Protests on such a large scale were unthinkable just a few months ago as the economy boomed with record high oil prices and as the Kremlin tightened its grip over almost all aspects of society, the BBC's Richard Galpin in Moscow says.
But now with the economy in deep trouble, there is real fear amongst ordinary people about what the future will hold, he says.
He adds that unemployment is rising rapidly, as are the prices of basic food and utilities.
Putin's 'policy bankruptcy'
In Vladivostok, the anti-government demonstration was called by the Communist Party.
"The crisis is in the heads of the authorities, not in the economy!" chanted protesters.
The protest was joined by a local group angered by higher tariffs imposed on cars imported to the city.
The region has thrived on the car import business and the government's decision has led to job losses, correspondents say.
In Moscow, police detained a number of members of the radical National Bolshevik Party, including its leader Eduard Limonov.
Separately, our correspondent says he witnessed a small group of supporters of former world chess champion Gary Kasparov - who is now an opposition figure - being attacked by unknown masked men before later being arrested by police.
Earlier, about 1,000 supporters of the Communist Party were allowed by the authorities to hold their demonstration in the capital.
Party leader Gennady Zyuganov said the economic crisis had exposed the bankruptcy of Mr Putin's policies.
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