GENEVA, November 25. /TASS/. The videos showing how Ukrainian servicemen are shooting dead captive Russian soldiers are highly likely to be authentic, UN High Commissioner for Human Rights Volker Turk said in a statement released on Friday, noting that the UN Human Rights Monitoring Mission in Ukraine (HRMMU) had come to this conclusion.

"Our Monitoring Mission in Ukraine has conducted a preliminary analysis indicating that these disturbing videos are highly likely to be authentic in what they show," Turk said adding that ‘the actual circumstances of the full sequence of events must be investigated to the fullest extent possible, and those found responsible appropriately held to account."

The analysis of the videos conducted by the HRMMU "underlines the need for independent and detailed forensic investigations to help establish exactly what happened," the UN High Commissioner said.

"We understand the Ukrainian authorities have opened a criminal investigation into the events in Makiivka (or Makeyevka, where supposedly the events from the video took place - TASS)," Turk said.

"It is essential that all allegations of summary executions are investigated fully in a manner that is - and is seen to be - independent, impartial, thorough, transparent, prompt and effective," he added.

Turk called "on the parties to issue clear instructions to their forces that there should be no retaliation, no reprisals, against those they take as prisoners of war and to ensure that these instructions are fully complied with."

The UN High Commissioner for Human Rights recalled that "the rules governing armed conflict set out in the Geneva Conventions demand this."

Earlier, the Russian Investigative Committee launched a criminal case over the mass execution of captive Russian soldiers by the Ukrainian army. As the Investigative Committee said, "a video showing representatives of Ukrainian armed formations shooting at least eleven unarmed Russian servicemen who had been captured on the territory of the Lugansk People’s Republic" was the reason that the case was opened.