KYIV: A court in southern Russia convicted 15 captured Ukrainian soldiers on terrorism charges Friday after a trial that Kyiv denounced as a sham and a violation of international law.

The military court in Rostov-on-Don sentenced 15 men from the Aidar battalion, which Russia has designated a terrorist group, to prison terms ranging from 15 to 21 years.

The verdict marks the second mass trial of Ukrainian prisoners of war since March, when 23 members of the elite Azov brigade were convicted on similar charges in a trial that also was condemned by Ukraine as a violation of international law.

When the trial of Aidar members began in 2023, Ukraine's human rights envoy, Dmytro Lubinets, denounced it as “shameful” and charged that “Russia is making criminals out of those who defended their native land.”

Memorial, a prominent Russian human rights group, has designated the defendants as political prisoners. It has been argued that the trial violated international conventions protecting POWs, noting the defendants were facing trial just because they served with the Aidar battalion, not over any specific war crimes.

“This grossly violates the provisions of the Geneva Convention, which prohibits the prosecution of prisoners of war solely for their participation in an armed conflict,” Memorial said.

Russia has labelled both the Azov and Aidar groups as terrorist organisations and accused their members of war crimes. The volunteer units were created soon after Russia's 2014 annexation of the Crimean Peninsula, and they took active part in fighting against Russia-backed separatists in eastern Ukraine.

Aidar, Azov and other volunteer units eventually were integrated into the Ukrainian military. Both Aidar and Azov have been criticised over their origins as volunteer battalions that included fighters from far-right circles, although current members reject accusations of extremism and any ties to ultra-nationalist movements.

When the trial of Aidar members began in 2023, it initially involved 18 members. Two nurses who served with the battalion also went on trial, but they were returned to Ukraine as part of a prisoner swap. Proceedings against a driver serving with the battalion will be held separately.

The trial was held in a military court in the city of Rostov-on-Don, home to Russia's Southern Military District. It is about 100 kilometres (60 miles) east of the border with Ukraine.

Most of the trial was held behind closed doors, but journalists were allowed to cover the opening sessions and Friday's verdict.