A Kiwi soldier killed in Ukraine was fighting alongside other foreign troops trying to re-take an enemy trench, it has emerged.

Dominic Bryce Abelen was on leave away from the New Zealand Defence Force (NZDF) and was not on active duty.

He was based at Burnham Military Camp outside of Christchurch with the 2nd/1st Battalion Royal New Zealand Regiment.

Abelen's family, when approached by the Herald last night, declined to comment.

He had been fighting with Ukraine's International Legion on the frontline in the east of the war-torn country.

It's not clear how long he had been in the country but he had been with other Kiwis and already been engaged in other "contacts" with the enemy.

Sources have told the Herald that Abelen was involved in a joint operation targeting the re-taking of a frontline trench network.

Private Dominic Abelen kneels behind a barricade while engaging targets at Range 218, Marine Corps Base Camp Pendleton CA United States 2013 during Dawn Blitz. Photo / Cpl. Joseph Scanlan

During an assault at dawn, Abelen was killed in firefight and died instantly, sources say.

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Another American fighter with the international troops also died.

They also claimed many casualties on the other side.

Former soldier and No Duff Charitable Trust co-founder Aaron Wood today said it was only a matter of time before a New Zealander was killed in the fierce fighting.

"If anything, it's surprising it hasn't happened sooner, and more often," said Wood who likened the fighting there to "every bad nightmare story that came out of the eastern front circa 1944/45".

"When people engage in that, you're counting the days," he said.

"While it is obviously very sad that he was killed, he knew what he was doing. I don't mean to sound cliched or callous, it's more of a pragmatic approach.

"He would've known the risks and had been there a while... and quickly figured out whether or not it was for him … and the fact that he stayed, he was comfortable with it."

Ukrainian President Volodymyr Zelensky announced the formation of the International Legion for the Territorial Defense of Ukraine on February 27 which called for foreign volunteers to join the fight against Russia under the Ukraine flag.

Within 10 days, it had reportedly received 20,000 requests to sign-up from people across more than 50 countries.

Wood has been in touch with several former NZDF personnel who have answered Ukraine's global call for help.

Ukrainian servicemen fire to Russian positions from anti-aircraft gun in Kharkiv region, Ukraine, early Wednesday, Aug. 24, 2022. Photo / AP

He says it would total around 100 people, with some being there for a brief period, others returning for multiple trips, and a few who have been there for the duration of the war.

The number at "the tip of the spear" like Abelen numbered "in the very low tens", Wood said, along with doctors, medics, and others in support.

Each individual has their own reasons for going, Wood said, ranging from those wanting to stand up against Russian aggression in what they see as a "righteous fight", to those servicepeople who trained for years but maybe never had the chance to put their skills or mettle into action, and the many "at a loss" after leaving the NZDF and struggle with the transition to civvy-street.

Earlier this month, the government announced it was sending a further 120 NZDF personnel to Britain to help train Ukraine soldiers as part of an international effort to help Ukraine continue to defend itself against Russia's illegal war.

It followed a completed deployment of 30 NZDF personnel in May to train Ukrainian military personnel in operating artillery.

"New Zealand has been clear that we will continue to answer the call of Ukraine for practical support as they defend their homeland and people against Russia's unjustified invasion," Prime Minister Jacinda Ardern said on August 15.

"We know that one of the highest priorities for Ukraine right now, is to train its soldiers, and New Zealand is proud to stand in solidarity alongside a number of other countries to answer that call."