Zelensky demands global response to beheading of soldiers in video

"This is a video of Russia as it is," Zelensky said in a video posted on Wednesday. He said it was neither an accident nor an isolated incident and demanded that terror must lose. No one would understand if state leaders did not react to the video, he said. "Action must be taken now!"

Meanwhile, Ukrainians must focus on the front and drive the occupiers out of the country. "Smashing the occupier, sentences for the murderers and a tribunal for the state of evil," are the main tasks now, Zelensky said.

His comments came after a video was shared in social media late on Tuesday which seems to show a Ukrainian prisoner of war being beheaded by a Russian soldier.

The trees in the video are green, suggesting the video was recorded last year.

The Ukrainian secret service is investigating the video. "We will find these brutes. If necessary, we will find them wherever they are: underground or from beyond the grave," said Vasyl Malyuk, chief of the Security Service of Ukraine (SBU).

In response to the video, Kiev's Foreign Minister Dmytro Kuleba called Russia "worse" than the Islamic State terror group and demanded Russia's expulsion from the United Nations.

Ukraine has been trying to repel a full-scale Russian invasion for more than 13 months, aided by Western allies.

The UN recently accused both warring parties of serious war crimes, including executions of prisoners of war.