Ukraine's nuclear energy authority on Friday published a video of what it said were four Russian guards who had accompanied a delivery of fuel elements, visibly uncomfortable as they made statements criticising Russia's military operation in Ukraine.
The authority, Energoatom, said on its Telegram channel that the men had accompanied a shipment of Russian fuel rods to Ukraine's Rivne nuclear plant last month.
Russia's nuclear power body, Rosatom, issued a statement demanding "the employees' speedy and safe return home", according to the Russian news agency RIA.
The video, which has obvious cuts, shows the four employees sitting behind a table, speaking haltingly in low voices to identify themselves as Rosatom employees.
They explain that they arrived in Ukraine on Feb. 22 with the fuel elements for the Rivne plant, and say they finished their contracted work on March 17.
Three of the men make statements criticising Russia's incursion into Ukraine, one looking repeatedly to the side of the camera as he speaks.
One says the men have seen for themselves how their compatriots have killed children and mothers. Another says the men do not understand how Russian officers could give orders to fire on nuclear plants.
"We do not want to participate in this or have anything to do with it," says the last to speak. "After everything we have seen, we are afraid to return."
Russia sent tens of thousands of troops into Ukraine on Feb. 24 in what it called a "special operation" to weaken its southern neighbour's military capabilities and root out people it called dangerous nationalists.
It says it does not target civilians, and that fighting and apparent shelling around the Zaporizhzhia nuclear plant were the result of a Ukrainian "provocation".
Rosatom said the men had made the delivery on Feb. 23, and that Energoatom had said they were being escorted back to Russia by Ukrainian SBU intelligence officers. Rosatom said that by Friday, they had not returned.
Energoatom did not immediately respond to a request for comment.
(Reporting by Reuters; Writing by Kevin Liffey; Editing by Daniel Wallis)