Ukraine vowed on Tuesday to take revenge against Russia, blaming the Kremlin for a captured soldier apparently being riddled with bullets in a viral video after using a pro-Ukrainian slogan.
The footage appears to show a detained Ukrainian combatant standing in a shallow trench, smoking, and being shot to death with multiple automatic weapons after saying "Glory to Ukraine".
Officials in Kyiv have blamed Russian forces and called for the International Criminal Court to probe the incident, which AFP could not independently verify.
The apparent victim's last words were trending online in Ukraine this week and the footage has spawned a new war-time meme in Ukraine celebrating the armed forces.
Many Ukrainians and social media users, who support Kyiv against Russia's invasion, posted a picture of the killed man online.
"The deceased is a serviceman of the 30th separate mechanised brigade -- Tymofiy Mykolayovych Shadura," the Ukrainian military said on Tuesday, citing initial findings.
Shadura has been missing since February 3 amid fighting near the eastern Ukrainian city of Bakhmut and his identity would be confirmed when his remains were returned, the military added.
"Revenge for our hero's killing is inevitable," it added.
Brigade spokesman Anatoliy Yavorsky said Shadura was born in 1982 and was from the region of Zhytomyr west of Kyiv. He was mobilised in December.
Kyiv has said his remains were still in territory held by Russian forces.
Another soldier?
Ukrainian journalist Yuriy Butusov, however, identified the deceased man as 42-year-old Oleksandr Matsiyevsky from the northern city of Nizhyn.
Butusov posted a picture on Facebook of Matsiyevsky, who resembled the Ukrainian soldier from the viral video.
The prominent reporter said Matsiyevsky, who had a 19-year-old son, went to the front voluntarily. He was buried in Nizhyn last month, he added.
AFP could not independently determine the origins of the footage or whether it showed a Ukrainian serviceman.
The head of the Wagner mercenary group, which has spearheaded Russia's assault on Bakhmut, said there was no evidence to link his fighters to the killing.
But Wagner chief Yevgeny Prigozhin said that if details emerged linking his group to the incident, then "we will certainly look into it in detail".
In an address to the nation on Monday, Ukrainian President Volodymyr Zelensky said the video showed Russian forces "brutally killing" a Ukrainian serviceman.
"We will find the murderers," he vowed.
Foreign Minister Dmytro Kuleba has called for the International Criminal Court to probe the footage.
The Hague-based Court did not immediately respond to an AFP request for comment.
Marta Bo, an international criminal and humanitarian law expert at The Hague-based Asser Institute, said that killing prisoners of war was a "grave breach of the Geneva Convention".
"States are under the obligation to investigate and prosecute such a violation of international humanitarian law," she told AFP.
Moscow and Kyiv have repeatedly accused each other of killing prisoners in the year since Russia invaded Ukraine.