A former British soldier was killed fighting for the Ukrainian armed forces, his family sources said.
Jordan Gatley, who left the British army in March and travelled to Ukraine, was described as “a hero” by his father Dean in a tribute on social media.
He died in the battle for the eastern city of Severodonetsk, which has witnessed intense fighting in recent days.
The Foreign Office has said it is “supporting the family of a British man who has died in Ukraine”.
Gatley’s father wrote in a Facebook post that his son had been helping train local forces. He added that Jordan was fatally shot on the front line while defending the city and the family was informed of his death on Friday.
He had gone to Ukraine to help “after careful consideration”, he added.
According to the Facebook post, the family “had several messages from his team out there telling us of his wealth of knowledge, his skills as a soldier and his love of his job”.
“His team say they all loved him, as did we, and he made a massive difference to many people’s lives, not only soldiering, but also by training the Ukrainian forces,” the statement continued.
“Jordan and his team were so proud of the work they were doing and he often told me that the missions they were going on were dangerous, but necessary.
“He loved his job and we are so proud of him,” Mr Gatley wrote, adding: “He truly was a hero and will forever be in our hearts.”
Mykhailo Podolyak, an adviser to Ukrainian President Volodymyr Zelensky, tweeted that Jordan Gatley was a “true hero”.
“We will always remember his contribution to the protection of Ukraine and the free world,” Podolyak wrote.
According to BBC Gatley served in the British army as a rifleman with the Edinburgh-based third battalion of The Rifles and was discharged from the forces in March before travelling to Ukraine.
There has been fierce street fighting in Severodonetsk with heavy artillery said to be causing huge casualties for both Russian and Ukrainian forces.
The region’s governor Serhiy Haidai has told Ukrainian TV that Russian shelling has caused a huge fire at a chemical plant in the city. Up to 800 civilians are hiding in underground bomb shelters at the plant, Ukrainian officials have estimated.