RIGA, Latvia — Prominent Russian opposition politician Vladimir Kara-Murza, facing up to 25 years in prison on treason charges for criticizing Russia's war against Ukraine, told a Moscow court on Monday that his trial had turned the clock back to the 1930s during the height of the Stalinist political repressions.

If the court accepts the prosecutor's request for the maximum 25-year term, it would be the harshest punishment to date of a politician or activist for criticizing Russia's war against Ukraine.

Kara-Murza, who is an opinions contributor for The Washington Post, spoke during a hearing on Monday ahead of a verdict that is expected on April 17. He described the charges as "unfounded, illegal and politically motivated" in comments on Facebook. His lawyers said the trial, which began last month, had been rushed, with it handled much more swiftly than usual treason cases.

He remained defiant in his final statement to the court, rejecting the judge's call that he must show remorse.

"I'm in jail for my political views. For speaking out against the war in Ukraine. For many years of struggle against Putin's dictatorship," he said. "Not only do I not repent of any of this, I am proud of it." He even declined to request an acquittal.

"For a person who has not committed any crimes, acquittal would be the only fair verdict," he said. "But I do not ask this court for anything. I know the verdict."

The United States State Department has described the charges as false and sanctioned Russian officials involved in the case for "gross violation of human rights."

Kara-Murza was the victim of two suspected poisoning attacks in Russia in 2015 and 2017. The Bellingcat investigative news site has reported that Kara-Murza was trailed repeatedly by the same team of agents from the Federal Security Service that poisoned the opposition politician Alexei Navalny in August 2020.

Since he was arrested last April, Kara-Murza has lost 48 pounds in pretrial detention, and his health has declined sharply, according to his lawyers, raising fears that he would not survive a long jail term.

"I was sure that after two decades in Russian politics, after all I had seen and experienced, nothing would surprise me. I must admit that I was wrong," he told the court, criticizing the trial's secrecy, the contempt for legal norms, and the harshness of the sentence the prosecution demanded.

But he expressed certainty that a day would come in Russia "when the darkness over our country will dissipate," and "those who kindled and unleashed this war, rather than those who tried to stop it, will be recognized as criminals."

Amid repeated military failures and setbacks, Putin has blamed the West for the war and suspended the last nuclear arms reduction treaty with the United States, plunging relations between Washington and Moscow into their most serious crisis since the Cold War.

The recent arrest of American journalist Evan Gershkovich, a correspondent for the Wall Street Journal during a reporting trip in Russia, and his indictment for espionage charges last month marked yet another new low in relations. Gershkovich, the Wall Street Journal, and State Department have all rejected the espionage charges.

In the earlier comments on Facebook, Kara-Murza called his own charges incomprehensible.

"I do not understand how public criticism of the current government can be qualified as high treason," Kara-Murza wrote. "It is incomprehensible to me how obvious and confirmed facts about the crimes committed during the aggression of Putin's regime against Ukraine can be presented as 'deliberately false information' and the obvious lie — on the contrary, as the only truth."

Kara-Murza, 41, is a longtime critic of Putin who campaigned for international sanctions against Russian officials responsible for state repression of Russian activists, politicians and whistleblowers.

Kara-Murza was initially charged with spreading disinformation about the Russian military after a speech to the Arizona House of Representatives about Russia's bombings of Ukrainian cities. Later other charges, including treason and cooperating with an undesirable organization, Open Russia, were added.

According to Kara-Murza's lawyer, Vadim Prokhorov, the treason charges related to three speeches Kara-Murza gave in Lisbon, Helsinki and Washington in which he publicly criticized Russian authorities.

The prosecutor, Boris Loktionov, demanded the maximum term of 25 years, claiming that Kara-Murza had discredited Putin and damaged Russian state interests. "This is our enemy who must be punished," Loktionov said, according to Russian media.

Russian rights groups have criticized the charges as politically motivated. Western governments and human rights organizations have called for his release.

An editorial in The Post last week described the trial as "a travesty of justice" that "reveals the deepening depravity of President Vladimir Putin's dictatorship."

Kara-Murza's is suffering from spreading numbness affecting his feet and his left hand, a condition prison doctors have diagnosed as polyneuropathy, caused by damage to peripheral nerves, according to his lawyers.

In a column for The Post last year Kara-Murza described the Kremlin's claims that Ukrainian leaders were neo-Nazis and the West was to blame for the invasion as "a total lie."

"After years of appeasing the Kremlin, Western leaders are learning the hard way that the instability, repression and conflict Putin is causing will resolve only when he is out of power," he wrote.

Kara-Murza is a strong supporter of the Magnitsky Act, which allows sanctions against those responsible for rights abuses. The law, named after Russian tax auditor and whistleblower Sergei Magnitsky who died in prison in 2009, has been enacted by the United States, Britain and other Western nations.

The judge in Kara-Murza's case, Sergei Podoprigorov, is under sanctions by the United States and Britain for his role in the jailing of Magnitsky. The United States has brought sanctions against six Russian officials, including three judges, for their roles in Kara-Murza's case.

Amid a flurry of recent espionage and treason cases in Russia, the constitutional committee of the State Duma, Russia's lower house of parliament, on Monday approved an amendment increasing the maximum penalty for treason to life imprisonment.

In Ufa, Liliya Chanysheva, a member of Navalny's team, is facing up to 18 years in prison if convicted of forming an "extremist" organization.

Navalny is serving a term of more than 11 years in jail for fraud, contempt of court and parole violations, charges he says are political and have been criticized by the European Court of Human Rights.

Russian authorities last year added new charges of promoting terrorism and extremism, according to Navalny, meaning he could face a total sentence of 30 years.

The Washington Post's Natalia Abbakumova in Riga, Latvia, contributed to this report.