Jordan Gatley, a former member of the British Army, has become the second Briton killed fighting for Ukraine in its struggle against Russian forces, his family has said.
Gatley was killed in the battle for the eastern Ukraine city of Syevyerodonetsk, site of brutal fighting as Ukrainian forces seek to prevent the Russian takeover of the area.
His family said he left the British military in March and traveled to fight for Ukraine "after careful consideration."
The British Foreign Office did not provide details but said, "We are supporting the family of a British man who has died in Ukraine."
He is the second Briton reported to be killed in the conflict.
In April, the British government said a citizen had been killed in Ukraine. He was not named by the government, but British media identified him as Scott Sibley, a military veteran.
The report comes as two British fighters and a Moroccan face the death penalty imposed by Moscow-backed separatists after they were captured in fighting in eastern Ukraine.
The British government and other Western countries have condemned the separatists' actions, calling them a violation of the Geneva Conventions.