Alexei Navalny, a jailed Russian opposition politician, Tuesday said he has been placed in solitary confinement for the third time this month. Navalny is a vocal critic of President Vladimir Putin, has organised anti-government demonstrations and founded the Anti-Corruption Foundation (FBK).

Navalny has been detained and placed on house arrest on several occasions due to public criticisms of the government. He is currently serving a nine-year sentence for parole violations, fraud and contempt of court. In May, authorities announced that he could face up to an additional fifteen years imprisonment for new criminal charges. Navalny has denied all charges against him and claims that they are politically motivated.

On Tuesday, Navalny said he was initially placed in solitary confinement for three days, but his stay was extended first to five days and then to seven days. Navalny attributes his treatment to his political activism. He has helped formed trade unions in prison which he claims “causes great irritation.” Navalny called for his supporters to “lend us a hand and contribute to the punishment of those who deserve to be punished” by supporting the FBK’s list of 6,000 bribe-takers, warmongers, and propagandists who enable Putin.