Forces from Russia's Wagner Group on Wednesday found the body of one of two British voluntary aid workers reported missing in eastern Ukraine, the private military firm said in a statement.
It did not mention the name of the dead man but said documents belonging to both Britons had been found on his body.
A photo posted alongside the statement appeared to show passports bearing the names of Andrew Bagshaw and Christopher Parry, the two missing workers.
Ukrainian police said on Monday they were looking for the pair who went missing in east Ukraine, the scene of heavy fighting between Ukrainian and Russian forces.
"Today the body of one of them was found. Documents for both Britons were discovered with him," said the Wagner statement. It did not give details on where the body was found.
Ukrainian police said the two left the city of Kramatorsk for the town of Soledar on Friday morning and were reported missing on Saturday evening after contact with them was lost.
A spokesperson for Britain's Foreign Office said: "We are supporting the families of two British men who have gone missing in Ukraine."
(Reporting by David Ljunggren and Ron Popeski; additional reporting by and Kylie MacLellan in London;Editing by Chris Reese and Cynthia Osterman)