KYIV — Moscow swapped high-profile commanders of Mariupol's Azov Regiment in return for a key ally of Russian President Vladimir Putin in the largest prisoner exchange since the full-scale invasion of Ukraine began in late February.

The deal that saw a total of 215 Ukrainians released included 188 defenders famously holed up for months in the key southern port's Azovstal steel mill after Russian forces besieged the city.

Out of the 108 members of the Azov Regiment that were exchanged on Wednesday, five military commanders were transferred to Turkey, Ukrainian President Volodymyr Zelensky said.

They will stay in this country "in absolute safety and in comfortable conditions until the end of the war" as part of an agreement brokered by Turkish President Recep Tayyip Erdogan, according to the Ukrainian leader.

In return, Russia has received a total of 55 prisoners, including former Ukrainian MP Viktor Medvedchuk, a close associate of Russian President Vladimir Putin, who was accused of high treason in Ukraine, Zelensky said in his daily address on Wednesday night.

Medvedchuk, a pro-Kremlin oligarch who Putin referred to as "a personal friend", was the most high-profile prisoner swapped on Wednesday. He was caught by the Security Service of Ukraine, SBU, on 12 April as he attempted to flee the country while masquerading in a Ukrainian military uniform.

Earlier on Wednesday, a group of ten foreign captives -- including five British men, two Americans, a Swede, a Croat, and a Moroccan -- have been released from jail in separatist-controlled east Ukraine in a deal negotiated by Saudi Arabia.

Several of the men had been sentenced to death by a court in the Donbas region but were given their freedom as part of a prisoner exchange.

British Prime Minister Liz Truss said their release ended "months of uncertainty and suffering for them and their families".

Truss thanked both Zelensky and the Saudi government for their part in helping secure the release of the men.

"Russia must end the ruthless exploitation of prisoners of war and civilian detainees for political ends," said Truss.

British lawmaker Robert Jenrick said one of the men was Aiden Aslin, 28, who had been sentenced to death after he was captured in eastern Ukraine.

“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. As they are united as a family once more, they can finally be at peace.”

The former captives arrived in Saudi Arabia from Russia. Saudi authorities said in a statement they were "working to facilitate the procedures for their safe return to their respective countries."

The deal was facilitated by Crown Prince Mohammed bin Salman, the de facto leader of Saudi Arabia, who met with a Ukrainian envoy to confirm the deal.

The Moroccan national was identified as the 22-year-old Brahim Saadoun, who fought in the Ukrainian army after moving to the country in 2019. Saadoun had also been sentenced to death for alleged "mercenary activities" in the Russian-controlled Donetsk.

Sweden and Croatia also confirmed the release of their citizens and thanked Ukraine and Saudi Arabia. The Croatian, Vjekoslav Prebeg -- detained in Ukraine since April -- will return home on Thursday, Croatia's foreign ministry said.

Two US military veterans who disappeared three months ago while fighting Russia with Ukrainian forces were among the ten prisoners released.

Alex Drueke, 40, and Andy Huynh, 27, went missing in the Kharkiv region of northeastern Ukraine near the Russian border on 9 June. Both had traveled to Ukraine on their own and became friends because both are from Alabama.

The families announced their release in a joint statement, saying they were both now at the American Embassy in Saudi Arabia. — Euronews