Navalny has called for demonstrators to protest Saturday outside the mayor's office against the rejection of several opposition candidates from the ballot for this fall's Moscow city council elections.
In a short video on social media, Navalny said he was seized by police outside his home on Wednesday morning as he went out for a run and to buy flowers for his wife's birthday. His lawyer Olga Mikhailova told the Interfax news agency that Navalny had been charged with organizing an unauthorized gathering.
Conviction could carry a penalty of 30 days in jail and a fine of up to 300,000 rubles ($4,600).
After the candidates for city council were rejected on the grounds of invalid signatures on their nominating positions, protesters held an unsanctioned demonstration outside the city election commission.
Russia's Investigative Committee on Wednesday said it was opening a criminal case over that demonstration, although potential charges were not specified.
The head of the voters' rights committee of the Presidential Human Rights Council, Ilya Shablinsky, was quoted by Interfax as saying the move was "complete nonsense ... This whole chain of actions by the authorities means that real competition is not allowed."
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