Russia's top investigator said on Wednesday that more than 30 Ukrainians had been given long jail terms in Russian-held Ukraine for committing what he described as serious crimes such as killing civilians.
Alexander Bastrykin, head of the Investigative Committee, Russia's equivalent of the US FBI, said courts operating on territory in parts of the Luhansk and Donetsk regions controlled by Russian forces had been working hard to jail people who had fought on the Ukrainian side against Russian forces.
"After the liberation of Mariupol and other settlements, many Ukrainian nationalists surrendered. In the course of further work, we began to establish their involvement in crimes against peace and human security, including the killing of civilians," Bastrykin told Russia's TASS news agency.
He said 90 criminal cases had been sent to courts.
"Based on the evidence gathered, courts have already convicted more than 30 defendants, sentencing them to long terms of imprisonment and some to life imprisonment," he said.
Which Ukrainians have been accused of war crimes by Russia?
President Vladimir Putin said in April last year that Russia had taken control of Mariupol as part of what he calls its special military operation after a siege that Ukraine said had killed tens of thousands of civilians and left the port city a wasteland.
Reuters could not independently verify the alleged war crimes referred to by Bastrykin. Ukrainian state prosecutors, who accuse Russian forces of committing numerous crimes in what they and the West call a brutal war of conquest, did not immediately respond to a request for comment.
Ukraine's parliamentary commissioner for human rights did not immediately reply either.
Bastrykin said in July last year that Moscow had charged 92 members of Ukraine's armed forces with crimes against humanity and proposed an international tribunal backed by countries including Bolivia, Iran and Syria.
Russian media on Tuesday reported that a former deputy commander of a Ukrainian militia unit had been sentenced by a Russian court to 16 years in a penal colony for taking part in what Moscow considered an illegal armed group and for receiving terrorist training.
Russia is itself under pressure for alleged war crimes. The International Criminal Court (ICC) issued an arrest warrant in March against Putin, accusing him of the war crime of illegally deporting hundreds of children from Ukraine. The Kremlin has rejected the allegation as false.