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Before the planned protests by the opposition on Saturday, other confidants of the Kremlin critic Alexei Navalny were arrested.
On Friday the police took Navalny's office managers in Vladivostok and Tyumen and two other employees in Novosibirsk and Kaliningrad into custody, the government critic's team and the human rights organization OWD-Info announced.
Navalny was arrested in Moscow on Sunday immediately after his return from Germany.
In Berlin he had been treated after a poison attack in August for which the opposition officials hold the Kremlin responsible.
On Monday, a Russian court rushed to sentencing him to 30 days in prison for violating suspended sentences.
The followers of Navalny then called for demonstrations on Saturday in around 65 cities across the country.
Research published by Navalny's team on an alleged luxury palace owned by President Vladimir Putin continued to heat the mood.
"Preventive measures" announced
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The attorney general's office warned on Thursday of further calls for protests and announced "preventive measures".
Police later arrested several of Nawalny's confidants.
Among them are his spokeswoman Kira Jarmysch and the well-known activist Lyubov Sobol, who will have to appear for a court hearing on Friday.
Sobol are accused of calling for unauthorized rallies.
According to her lawyer, she faces a fine of the equivalent of 4,000 euros.
Since she has a young child, a prison sentence is unlikely.
According to her lawyer, Jarmysch could be sentenced to ten days in prison because of the protest calls.
After Navalny's arrest, which had also been condemned internationally, many Russians showed solidarity in the online networks and called for active participation in the protests.
Several prominent Russian actors, musicians and athletes also expressed their support for Navalny.