Some 1,500 people gathered for the unsanctioned protest in the center of Moscow, police said in a statement. 

Navalny, who was banned from participating in the March presidential elections due to a five-year suspended sentence, called on Russians to hold a day of rallies across the country on the eve of Vladimir Putin's inauguration, scheduled for May 7.

The activist himself was detained at an unsanctioned rally in the Russian capital on Saturday for violating rules on organizing public demonstrations, police confirmed.

As of 6:30pm local time, some 300 people had been detained in Moscow during the unsanctioned protests, police said.

Earlier, the prosecutor’s office in Moscow said that it had offered the event’s organizers several venues for the rally, but all options were rejected. The office then warned the protesters that other venues where they were planning to march were unauthorized.

Around 2,000 took part in the another unsanctioned protest in St. Petersburg, according to local police. Some 200 “active participants” in the protest have been detained.