Aiden Aslin, 28, was sentenced last month for “mercenary activities” because he was captured while fighting as a foreigner (he is a British citizen) for Ukraine’s army. Fellow Briton Shaun Pinner and Moroccan Brahim Saadoun were handed the same sentence alongside him.
The court, located in the Donetsk People’s Republic, is not internationally recognised.
The court hearing has also been described as “hasty”.
Video footage has now emerged of Aslin singing “The State Anthem Of The Russian Federation”.
He does this while in a small room with bars over the windows.
The prisoner is unshaven and has short hair.
Aslin is originally from Newark in Nottinghamshire.
Former US police officer John Dougan, who moved to Russia in 2016 and now styles himself as a reporter, stands by his side during the rendition and afterwards declares he has “goosebumps” on his arms.
Sharing the video on social media, journalist Kevin Rothrock wrote: “Yikes. Exiled US conspiracy theorist John Dougan has apparently interviewed Aiden Aslin, the captured UK volunteer soldier now awaiting execution in the DNR.
In a damning indictment, Russia’s ambassador to Britain this month told Reuters he was surprised by the apparent lack of effort from London to get Aslin and Pinner released.
Andrei Kelin said: “We had a formal request here in London and in Moscow about these two guys – that they exist – and a phrase like ‘we put all responsibility on Russia for them’.
“There was no demand for mediation, no demand for their release or anything like that. ‘Let’s talk about their fate and what can be done in this situation’. Nothing.”
He also responded to the suggestion Moscow could put pressure on DPR officials to release the men: “And so what?
“Has anyone from London asked us to do this? No.”
Britain’s Foreign Ministry insisted, however, it was doing “everything we can to support the men”.