Ukraine on Sunday launched an investigation into what it said was an "execution" by Russian forces of two unarmed Ukrainian soldiers who had signaled their intention to surrender.
The day before, a short video was posted on the messaging app Telegram, showing two men coming out of a shelter, one with his hands above his head, before lying on the ground in front of another group of soldiers.
This is followed by what appears to be gunfire and rising smoke, after which the video cuts off abruptly.
AFP was able to confirm the authenticity of the video.
The public prosecutor's office in the eastern Ukrainian region of Donetsk said that according to "preliminary information," the video was filmed near the village of Stepove, close to Avdiivka, a town that has become the latest flashpoint in the war.
"The video shows how a group of people in Russian uniforms shoot at close range two unarmed servicemen in the uniforms of the Armed Forces of Ukraine, who surrendered as prisoners," the prosecutor's office said.
"Investigators and prosecutors have started an investigation," it added.
"The killing of prisoners of war is a gross violation of the Geneva Conventions and is classified as a serious international crime."
Ukraine's human rights ombudsman, Dmytro Lubinets, condemned the incident as a "war crime."
There was no official comment from Moscow as of Sunday afternoon.
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