Police in several Russian cities have detained supporters of opposition leader Alexei Navalny on the eve of his rallies against President Vladimir Putin’s inauguration.

Putin is scheduled to officially assume his fourth presidential term on Monday, with Navalny calling on supporters to take to the streets in at least 90 cities for “He’s Not Our Tsar” protests on Saturday.

Navalny supporters have been detained in St. Petersburg, Krasnoyarsk, Tambov, Krasnodar and Cheboksary, Interfax reported Friday, citing activists and their social media pages.