Russian state TV aired a video on Monday of Aiden Aslin and another captured British fighter identified as Shaun Pinner asking to be exchanged for Viktor Medvedchuk, a wealthy Ukrainian businessman close to President Vladimir Putin.

“The video of Aiden speaking under duress and having clearly suffered physical injuries is deeply distressing,” Aslin’s family said in a statement released by his local MP Robert Jenrick.

“Using images and videos of prisoners of war is in contravention of the Geneva Convention and must stop.”

The statement said the family was in touch with the UK Foreign Office “to ensure the Russian authorities meet their obligations to prisoners of war under international law”.

It added that it was seeking “to secure the release of Aiden and Shaun”.

Aslin moved to Ukraine in 2018 and joined the Ukrainian Marines around four years ago. He was captured last week before appearing in the video, looking haggard.

Along with Pinner, he appealed for a prisoner swap with Putin ally Medvedchuk, who was recently arrested in Ukraine.