Ten prisoners, including Americans, have been released as part of a Russia-Ukraine exchange, Saudi Arabia says.

Ten prisoners of war, including U.S. and British citizens, have been transferred to Saudi Arabia as part of an exchange between Russia and Ukraine, Saudi officials said on Wednesday.

The Saudi foreign ministry said on Twitter that Mohammed bin Salman, the Saudi crown prince, had mediated the release.

Among those released were Alex Drueke, 39, a former U.S. Army staff sergeant who served two tours in Iraq, according to his aunt, Dianna Shaw. Andy Tai Ngoc Huynh, 27, a former Marine, was also released, according to Ms. Shaw, who said she had been texting Mr. Huynh’s family. “We’re just so deeply grateful,” Ms. Shaw said.

Mr. Drueke and Mr. Huynh volunteered to fight in Ukraine and were captured near the city of Kharkiv on June 9 while fighting alongside other foreign soldiers.

Five British citizens who had been held in Ukraine by Russian-backed proxies have been released, Prime Minister Liz Truss said, calling it “hugely welcome news.” Ms. Truss thanked President Volodymyr Zelensky of Ukraine and Saudi Arabia for their help securing the citizens’ release.

“Russia must end the ruthless exploitation of prisoners of war and civilian detainees for political ends,” she said.

In addition to the United States and Britain, the prisoners released were from Morocco, Sweden and Croatia. The Saudi ministry saidit was working to return those released to their home countries.

Robert Jenrick, a Conservative member of the British Parliament, wrote on Twitter that Aiden Aslin was among the prisoners who was released. Mr. Aslin’s hometown of Newark is in Mr. Jenrick’s district.

Mr. Aslin was one of three men — including Shaun Pinner, a British citizen, and Brahim Saadoun, a Moroccan — who were sentenced to death in June by a court in Russia-occupied eastern Ukraine Prosecutors had accused the three men of being mercenaries and terrorists who were seeking to violently overthrow the government of the Donetsk People’s Republic, one of two breakaway regions in eastern Ukraine that Russia has recognized.

Their sentences had alarmed human rights advocates and Western governments, raising questions about the protections afforded to thousands of foreign-born fighters serving in Ukraine, some of whom have been taken prisoner on the battlefield.

“Aiden’s return brings to an end months of agonizing uncertainty for Aiden’s loving family in Newark who suffered every day of Aiden’s sham trial but never lost hope,” Mr. Jenrick wrote. “As they are united as a family once more, they can finally be at peace.”