Navalny, 44, was detained on Jan. 17 when he returned to Moscow from Berlin, where he had spent months recovering from a near-fatal poisoning attack in August he blames on President Vladimir Putin.

His arrest triggered mass protests across Russia, with supporters taking to the streets in more than 100 cities for unsanctioned rallies urging his release.

The anti-corruption campaigner was charged with violating a 2014 suspended sentence for embezzlement by skipping out on check-ins with Russia’s prison service while in Germany. The European Court of Human Rights (ECHR) in 2017 ruled that Navalny’s 2014 conviction was “arbitrary and unreasonable.”