Kremlin critic and opposition leader Alexei Navalny was handed an eight-year prison sentence after being found guilty of fraud on Tuesday.
Investigators accused him of embezzling millions of roubles in donations to his anti-corruption organisations and of "contempt of court" during one of his previous hearings.
Navalny is already serving a two-and-a-half-year sentence for another fraud.
He says both cases are fabricated in a bid to silence him.
"Navalny committed a fraud, the theft of property from others by an organised group," said judge Margarita Kotova as she issued a guilty verdict earlier on Tuesday, according to an AFP journalist present in court.
Navalny, 45, has been on trial since mid-February within walls of his penal colony 100 km east of Moscow.
An activist renowned for his scathing investigations into corruption and the lifestyle of Russian elites, Navalny survived a serious poisoning in 2020, for which he holds President Vladimir Putin responsible.
He was arrested in early 2021 upon his return to Moscow, after recovering in Germany from what was considered to be the consequences of a Novichok nerve agent attack.
Other critical voices have been targeted by Moscow in recent months, including NGOs such as the human rights group Memorial and independent media outlets.
On Monday, Instagram and Facebook were banned after their parent company Meta was declared an "extremist organisation" by a Moscow court.