Ukraine’s Foreign Ministry condemned the attack on a prison in Russian-backed separatist-held territory on Friday and appealed to the International Criminal Court alleging Russia’s war crimes.

Russia said Ukraine claimed about 40 Ukrainian POWs were killed in Friday’s attack and claimed it was not involved in any war crimes in Ukraine.

“We call on the Prosecutor’s Office of the International Criminal Court to urgently draw attention to the atrocities of the Russian army in the context of the investigation of war crimes and crimes against humanity committed on the territory of Ukraine by citizens of the Russian Federation,” the Ministry of Foreign Affairs of Ukraine said in a statement.

He said the crimes in question coincided with “another Russian war crime, the bombing of prisons in occupied Olenivka, where it is believed that Ukrainians are being held as prisoners of war.”