The family of a captured British man fighting in Ukraine accused Russia on Wednesday of breaking the Geneva Convention after it broadcast a "distressing" video of him.
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 U.K. 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."
Prime Minister Boris Johnson told MPs on Wednesday: "I hope that he was treated with care and compassion."
He also said he "thoroughly" echoed Jenrick's assessment that the video represented "a flagrant breach of the Geneva Convention" and that "treating any prisoner of war in this manner is illegal."
Aslin moved to Ukraine in 2018 and joined the Ukrainian Marines around four years ago. He was captured last week beore 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.