Outspoken Kremlin critic and opposition leader Alexei Navalny was reportedly detained outside his home in Moscow on Saturday and injured while in police custody. Spokeswoman Kira Yarmysh announced the news on Twitter, saying he’d suffered a fractured finger after being detained by five riot police officers. He is expected to remain in detention until a court hearing on Monday over an anti-Putin protest in January. The 42-year-old has repeatedly been detained and arrested for organizing widespread protests against Russian President Vladimir Putin. His arrest comes ahead of a planned protest against the government’s controversial pension reform on Sept. 9. Navalny had urged residents in more than 90 towns and cities to take part in the demonstration under the slogan, “Putin is not our tsar.” Yarmysh said she believes his detention is meant to prevent him from taking part in that protest.