A Russian military court has provoked international outrage by sentencing the Ukrainian filmmaker Oleg Sentsov to 20 years in a high-security penal colony for supposed terrorism charges. The proceedings, which have been widely compared to the farcical show trials of the Stalin era, reflect Russia's intolerance of dissent in Crimea, which it annexed from Ukraine last year.

Sentsov, a Crimean native best known for his 2011 film Gamer, and Alexander Kolchenko, a 24-year-old Crimean activist, were arrested in May 2014 after protesting against the seizure of the peninsula. They were accused of having organized arson attacks against pro-Russia organizations, including the local office of Russia's ruling party, United Russia, and of conspiring to destroy a memorial to Vladimir Lenin in Simferopol, Crimea's capital.

The pair stood trial in the Russian city of Rostov-on-Don alongside one another and professed their innocence throughout the proceedings. Kolchenko received a sentence of 10 years.

Both men were tried as Russians, although they are Ukrainian and have never sought Russian citizenship. The Russian government denies that Sentsov and Kolchenko are political prisoners.

TV footage of the sentencing showed the two men locked in a courtroom cage. After the verdict was read out, they defiantly sang the Ukrainian national anthem together.

Sentsov had earlier said that Russian authorities tortured and beat him following his arrest in order to compel him to confess to false crimes and implicate others in them, which he refused to do. Prosecutors dismissed his injuries and bruises as the product of sadomasochistic equipment that they claimed to have recovered from his apartment.

In his closing statement to the court last week, Sentsov questioned the legitimacy of the trial and spoke out against Russia's role in the conflict in Eastern Ukraine.

"A court of occupiers by definition cannot be just," he remarked. "You perfectly well understand that there are no fascists in Ukraine. That Crimea was annexed illegally. That your troops are fighting in Donbas."

He also noted that Gennady Afanasyev, the prosecution's main witness against him and Kolchenko, had recanted his testimony, which Afanasyev said had been forced.

"He took a courageous and righteous step. I was very surprised by this and I am glad for him," Sentsov said. "It isn't even that it would cause a major scandal or create a problem and we would be acquitted. No, that couldn't happen. I am glad for him because he will be able to live the rest of his life and know that he is a human being who did not give in to fear even though they continue to threaten him, to pressure him, to kick him, to threaten him."

Sentsov and Kolchenko are just two of various Ukrainians who have been criminally charged in Russia. Military pilot Nadiya Savchenko is also facing trial in southern Russia, accused of killing two people. The United States has referred to them as Ukrainian hostages held by Russia.

In October 2014, the European Film Academy joined with the French Directors' Guild to voice opposition to Sentsov's prosecution. The European Film Academy also recently addressed an open letter against the trial to Russian President Vladimir Putin, his minister of internal affairs, and the director of the FSB, the state security agency that replaced the KGB. It was signed by directors that included Mike Leigh, Wim Wenders, and Ken Loach, and was accompanied by a long list of supporters.

From the moment when we learned that the Ukrainian filmmaker Oleg Sentsov was arrested by the Federal Security Service of the Russian Federation (FSB) in his house in Simferopol on 11 May 2014, we have been deeply worried," the letter said. "Having observed the trial and especially the fact that the key witness for the prosecution has retracted his testimony as 'given under pressure and duress,' we are shocked that the accusation of Oleg Sentsov having committed 'crimes of a terrorist nature' is still being upheld."

"This whole trial was designed to send a message," Heather McGill, Eurasia Researcher at Amnesty International, said in a statement. "It played into Russia's propaganda war against Ukraine and was redolent of Stalinist-era show trials of dissidents."

Ukrainian President Petro Poroshenko meanwhile offered words of support on Facebook.

"Hang on, Oleg," he wrote. "Time will pass, and those who organized this trial will find themselves in the dock."