Opposition activist Vladimir Kara-Murza has been sentenced to 25 years in jail for treason and other charges linked to his criticism of the war in Ukraine.
The Russian-British former journalist and politician is the latest of a number of Putin opponents to have been arrested or forced to flee Russia.
He has denied the charges and been vocally critical of his trial.
Last week, he told a Moscow court: “I subscribe to every word that I have said.”
“Not only do I not repent any of this, I am proud of it,” he added.
As well as criticising the so-called “special military operation” in Ukraine, Mr Kara-Murza has also spoken openly against President Vladimir Putin and his government’s crackdown on dissent.
The 41-year-old played a key role in persuading Western governments to sanction Russian officials for human rights abuses and corruption.
His 25-year sentence was the top number sought by prosecutors and is the longest sentence an opposition figure has received so far.
Mr Kara-Murza was arrested a year ago in Moscow, initially for disobeying a police officer. More serious charges were levelled at him once he was in custody.
His case was partly based on a speech he made to politicians in the US last year, where he said Russia was committing war crimes in Ukraine with cluster bombs in residential areas and “the bombing of maternity hospitals and schools”.
Those claims have been independently documented – but deemed false by Russian investigators who said the defence ministry did “not permit the use of banned means… of conducting war” and insisted Ukraine’s civilian population was not a target.
Another charge stemmed from an event for political prisoners at which Mr Kara-Murza referred to what investigators called Russia’s “supposedly repressive policies”.