UKRAINE has launched an investigation into a gruesome video that purportedly shows Russian troops beheading a Ukrainian soldier.

The video, which has yet to be authenticated, spread quickly online on Wednesday, triggering expressions of outrage by officials in both Kiev and Moscow as well as international organisations. 

The Kremlin called the footage “horrible” but added that it needed to be verified.

The video circulating online appears to show a man in green battledress wearing a yellow armband, as is typically donned by Ukrainian fighters. His screams are heard before another man in camouflage uses a knife to decapitate him.

Both Russian and Ukrainian troops have been accused of abuses during the conflict.

The International Criminal Court has issued an arrest warrant for Russian President Vladimir Putin for war crimes, alleging that he bears personal responsibility for the abduction of children from Ukraine.

The Kremlin denies that its forces have committed war crimes or targeted civilians.

Last year, Kiev vowed to investigate a video circulating online that allegedly showed Ukrainian forces killing Russian troops who appeared to be surrendering, but there has been no word yet from that probe.

The United Nations Human Rights Monitoring Mission in Ukraine said that “the latest incidents must also be properly investigated and the perpetrators must be held accountable.”