Police detained about 20 activists in downtown Moscow on Thursday, the Interior Ministry said.
“About 20 people were detained around Pushkinskaya Square as they attempted to hold an unsanctioned rally,” a ministry spokesman said.
All the detainees were taken to a local police station, he added.
He offered no indication of the detainees’ political affiliation.
Earlier in the day seven activists of the Solidarity opposition movement were detained on Red Square.
About 20 protesters were hauled in by police on Tuesday following Monday’s authorized opposition rally against Prime Minister and president-elect Vladimir Putin’s election on Sunday for a third non-consecutive term in office that turned into an unsanctioned demonstration resulting in the detention of about 250 people.