Dozens of Russian journalists and rights activists on Monday called on the authorities to free a prominent opposition politician facing up to 25 years in jail for alleged treason and other charges which they said were politically motivated. The appeal to release Vladimir Kara-Murza, 41, came ahead of a court hearing in Moscow as his trial, which the journalists likened to the political terror meted out by Soviet leader Josef Stalin in the 1930s, draws to a close. Russian state prosecutors on Thursday requested a 25-year prison sentence for Kara-Murza, a father of three and author and former journalist who holds Russian and British passports. He is expected to deliver a final speech at Monday’s hearing, his lawyer Vadim Prokhorov has said. Kara-Murza has spent years in opposition to President Vladimir Putin and has lobbied foreign governments and institutions to sanction Russia and individual Russians for purported human rights violations. Prosecutors accuse him of discrediting the Russian military and treason among other charges after he criticised Russia’s war in Ukraine – which it calls a “special military operation” – Moscow’s crackdown on dissent, and Putin. Shortly after sending tens of thousands of troops into Ukraine in February last year, Russia introduced sweeping wartime censorship laws which have been used to silence dissenting voices across society. “Discrediting” the army can currently be punished by up to five years in prison, while spreading deliberately false information about it can attract a 15-year jail sentence. At a time of war, pro-government politicians say unity across society is vital and have described Russian citizens questioning Moscow’s actions in Ukraine as part of a pro-Western fifth column trying to undermine the war effort. The letter petitioning for Kara-Murza’s release was signed by many journalists who have fled the country. It said Kara-Murza was merely being punished for his opposition to the war. “We demand that the Russian authorities, law enforcement officers and judges return to the path of justice. Prosecute murderers and criminals rather than honest and responsible citizens who dare to think and speak the truth,” the letter said. “Stop Russia’s new slide toward Stalinism and a totalitarian system.” There was no immediate response to the letter from the authorities who regard many of its signatories as traitors who crave the defeat of their own country on the battlefield. Kara-Murza and his supporters say he has twice survived being poisoned in the past. Russian authorities deny any involvement in the alleged attacks.