MOSCOW (AP) — A court in Russia on Tuesday rejected imprisoned opposition leader Alexei Navalny’s second appeal of a nine-year sentence.

The 46-year-old dissident is serving the sentence, handed to him in March, on the charges of fraud and contempt of court, in a high-security prison.

Navalny, Russian President Vladimir Putin’s fiercest foe, was arrested in January 2021 upon returning from Germany, where he had been recuperating from a nerve-agent poisoning that he blames on the Kremlin. Russian authorities deny the charge. He was sentenced to 2 1/2 years in prison for a parole violation that the West has called politically motivated.

In March, he was sentenced to nine years in a separate case on charges of embezzling money that he and his foundation raised over the years and of insulting a judge during a previous trial. Navalny has rejected the allegations as politically motivated. His first appeal was rejected in May.

Navalny’s arrest last year triggered the biggest protests seen in Russia in recent years. In response, Putin’s government unleashed a sweeping crackdown on his organization, associates and supporters.

Several criminal cases have been launched against Navalny individually, leading his associates to suggest that the Kremlin intends to keep him behind bars indefinitely.