The two volunteers were last spotted leaving for the city of Soledar.
The pair were attempting to assist an elderly woman when their cars were hit by a shell.
As part of a prisoner swap with Russia, the bodies of two British volunteers slain in eastern Ukraine in January have been found.
The bodies of Chris Parry, 28, and Andrew Bagshaw, 47, have been delivered to Ukraine, according to President Volodymyr Zelensky’s chief of staff.
There has been no word on when they would be handed over to British embassy personnel to be flown home.
The families of the men said they were killed during a humanitarian rescue.
On January 6, the two volunteers were last spotted leaving for the city of Soledar.
According to Mr. Bagshaw’s family, the pair were attempting to assist an elderly woman when their cars were hit by a shell.
Soledar had been the site of severe fighting, and Russia’s military claimed last month that it had conquered the Ukrainian salt-mine town after a long war. The claim was denied by the Kyiv government.
Despite the ongoing combat in Ukraine, Ukraine’s chief of staff, Andriy Yermak, announced on Saturday that 116 Ukrainian servicemen had been released.
He stated that released captives comprised Mariupol defenders, Kherson partisans, Bakhmut snipers, and two special operations soldiers.
Russia’s defense ministry said 63 personnel had been returned as part of a “complex mediation process”.
It stated that it included persons from a “sensitive category” thanks to the United Arab Emirates’ intervention, although it did not define what those people did.
It is the second prisoner exchange between the two countries this year.
According to Mr. Yermak, Ukraine is continuing its efforts to bring everyone home.
Mr. Parry and Mr. Bagshaw had been volunteering in the Donetsk region of eastern Ukraine.
In a statement issued by the UK Foreign Office last month, Mr. Parry’s family said his “selfless determination in helping the old, young, and disadvantaged” in Ukraine had made them “extremely proud”.
“We never imagined we would be saying goodbye to Chris when he had such a full life ahead of him. He was a caring son, fantastic brother, a best friend to so many, and a loving partner to Olga,” they said.
They added that Mr. Parry, originally from Truro in Cornwall, “found himself drawn to Ukraine in March in its darkest hour at the start of the Russian invasion and helped those most in need, saving over 400 lives plus many abandoned animals.”
Mr. Bagshaw was a British national who lived in New Zealand as a scientific researcher. Since April, he had been working as a volunteer in Ukraine.
In a statement, Mr. Bagshaw’s family said last month: “Andrew selflessly took many personal risks and saved many lives; we love him and are very proud indeed of what he did.
“The world needs to be strong and stand with Ukraine, giving them the military support they need now, and help to rebuild their shattered country after the war.”
“The world must be firm and stand with Ukraine, providing them with the military support they require now and assisting them in rebuilding their destroyed country after the war.”
Pete Reed, another foreign volunteer in Ukraine, was slain on Thursday in the eastern Ukrainian city of Bakhmut, which has seen significant combat in recent days.
Mr. Reed, a 33-year-old American volunteer assistance worker, was killed “while rendering aid,” according to a statement from Global Response Medicine, the humanitarian aid organization he created.
The UK government has already warned against all travel to Ukraine, warning there is “a real risk to life”.
British nationals who are still in Ukraine should leave immediately if it is safe to do so, according to the statement.
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