An Irish man has been "killed in action" in Ukraine, his family has confirmed.
Rory Mason, 23, was fighting in the International Legion for the Defence of Ukraine as part of the Ukrainian Armed Forces.
The native of Dunboyne, Co Meath was fighting in the Kharkiv region near the Russian border.
Mr Mason enlisted to fight in Ukraine last March. His father said he had "a deep sense of right and wrong and an inability to turn the other way in the face of injustice".
The International Legion for the Defence of Ukraine said Rory Mason was taking part in the Kharkiv counteroffensive with his unit and was "killed in action".
"While conducting operations, the unit came under attack," the legion said.
"We are in contact with the family and in coordination with them, following their wishes and instructions, the International Legion and the Armed Forces of Ukraine are handling the repatriation process.
"At this time, to protect operational security and the family's privacy we cannot release more information."
The statement added that "Rory's memory will live on in his unit, in the Legion and the Armed Forces of Ukraine".
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The Mason family learned of Rory's death from the Department of Foreign Affairs, which is providing consular assistance.
A spokesperson for the family said: "Given Mr Mason was killed on the front line of an active war zone, information on what occurred is limited and the family's priority at this point is to repatriate Rory’s remains."
The spokesperson added that he is deeply missed by his "heartbroken" family, his parents Rob and Elizabeth and his younger brother, 22, and sister, 21.
A man of 'drive, purpose and conviction'
His father said Rory "was a private young man of drive, purpose and conviction".
"Though we are deeply saddened at his death, we are enormously proud of his courage and determination and his selflessness in immediately enlisting to support Ukraine," he said.
"Rory was never political but he had a deep sense of right and wrong and an inability to turn the other way in the face of injustice. He had a long-standing interest in Eastern Europe, in travel and in learning new languages, including Russian.
"Those who fought alongside Rory speak of a truly brave and courageous man who could have left at any time but chose not to. In the words of a colleague who served with him, 'Rory was a man who from a glance could seem shy however when it came to actions and character he proved again and again he was a man of fortitude, principal and honour'.
"Rory was our son and we will miss him enormously. As our family is still trying to come to terms with Rory's death, we would appeal for privacy at this difficult time."
Before the war, Mr Mason had been working in Germany.
He attended Dunboyne National School and St Peter's College in Dunboyne.
In a statement, the community of Peter's College expressed their shock to hear of the death Mr Mason.
"St Peter's College is shocked to hear the news of the untimely death Rory Mason who we understand, was fighting for the International Legion for the Defence of Ukraine.
"The entire St Peter’s College community, students, past pupils, teachers and the Board of Management offer their condolences and deepest sympathies to Rory’s family at this very difficult time."
A Ukrainian MP said the Ukrainian people will forever thank Rory Mason and his family for all he did to help their country "in their great need".
Speaking on RTÉ's Today with Claire Byrne, Sviatoslav Yurash said it is very clear that people like Rory answered the call made by the free world.