Prisoners Held by Both Russia and Ukraine Appeal to Leaders for Help

High-profile prisoners held by both Russia and Ukraine, including two British fighters believed captured in Mariupol, appealed on Monday to be exchanged.

Viktor Medvedchuk, one of the richest tycoons in Ukraine and a close ally of President Vladimir V. Putin of Russia, appeared in a 34-second video posted on Twitter by the Security Service of Ukraine. Mr. Medvedchuk, 67, the leader of a Ukrainian political party, asked both Mr. Putin and the Ukrainian president, Volodymyr Zelensky, to exchange him for the people defending Mariupol as well as any civilians trapped in the besieged, shattered southern port city.

Mr. Medvedchuk, who had been under house arrest on treason charges when the war started but escaped, had been shown after he was captured on April 12, handcuffed, in military fatigues and looking disheveled and dazed. In his appeal on Monday, his hair was combed and he was wearing a zippered sweater.

Mr. Medvedchuk was considered particularly close to Mr. Putin, who was godfather to his youngest daughter.

Two British fighters for Ukraine apparently captured in Mariupol appeared on Russian state television, asking to be released in exchange for Mr. Medvedchuk. All three men seemed to be speaking while in detention. The two Britons made the suggestion at the prompting of a man not identified on camera, who showed them a clip from a news conference that Mr. Medvedchuk’s wife, Oksana, gave over the weekend asking that he be freed. That prompted speculation that the Russians, who controlled the interview process, had come up with the exchange idea.

It was unclear how free the Britons were to say what they wanted. The two — Shaun Pinner, 48, and Aiden Aslin, 28 — spoke separately in interviews broadcast Monday on Rossiya 24, a state channel. Both men requested that the British government offer assistance toward an exchange for Mr. Medvedchuk. “I’d like to appeal to the government to send me back home; I’d like to see my wife again,” Mr. Pinner said, addressing Prime Minister Boris Johnson directly in saying that both men needed help.

The two fought on the Ukrainian side in Mariupol, which Russian forces have almost captured entirely, other than the vast Azovstal steelworks complex. Both seemed in good health, if a bit battered and dirty, and Mr. Aslin had a gash in his forehead. The Geneva Conventions bar coerced interviews with prisoners of war.