Four crew members of an Australian Army helicopter - which was taking part in large-scale military exercises that include New Zealand soldiers - are missing after the chopper crashed into the ocean off the coast of Queensland, near Hamilton Island, late last night.
The NZ Defence Force says no New Zealand troops were involved in the crash.
Australian Defence Minister Richard Marles said the MRH90 helicopter, known as a Taipan, was engaging in a two-helicopter training mission and had four crew aboard when it crashed about 10.30pm.
Marles said the second chopper immediately began a search and rescue operation, which remains underway this morning.
The chopper was taking part in Exercise Talisman Sabre, which has been paused in the light of the accident.
Marles said the crew members' families had been notified.
Dubbed Exercise Talisman Sabre (also known as Saber depending on whether Australia or the US is leading), the action involves nearly 30,000 personnel from 13 nations including the United States, France, and Australia.
This year is the 10th iteration of the biennial exercise which focuses on the planning and conduct of a high-end, warfighting scenario.
Several Pacific Island countries - including Papua New Guinea, Fiji and Tonga - are participating for the first time.
The exercise involved securing a western corridor in the Townsville Field Training Area (60 kilometres south-west of Townsville), subdue defending enemies and allowing a brigade to advance through.
A range of helicopters, including the Royal New Zealand Air Force NH90s, were used to bring in more troops to join the 'offensive'.
About 100 Royal Australian Air Force and US Air Force aircraft took part in the air component of the exercise, according to the Australia's Defence Force news release this week.
Lieutenant Colonel Jacob Murray said it had been a number of years since partnering forces had teamed up in direct cooperation.
"This exercise is a critical step in reinforcing warfighting as our 'raison d'etre' whilst enhancing our ability to conduct land combat operations at scale."
According the New Zealand Defence Force's news release, this year's exercise is designed to improve combat readiness, exercise war-fighting skills and systems, and advance staff and force interoperability.
Australian Army Colonel Ben McLennan, commander of the Australian Defence Force's Combat Training Centre, said they were training to face a type of potential enemy which had capabilities across land, space, air, maritime and cyber.
Colonel Brian Baldwin, US Air Force Commander of the 13th Air Expeditionary Wing, said this was a chance to focus on training multi-domain threats and fights that are difficult to do over the east coast.
"This is the biggest, most complex Talisman Sabre we've undertaken, which brings its own challenges but also gives us an opportunity to keep developing the inner connective tissue between our two countries," he said.
The US Department of Defence website's news section said there has been a welcoming atmosphere from the Australians, adding there has been a steady stream of food trucks making their way to the camp and a gathering hosted by the Bowen Chamber of Commerce.
Exercise Talisman Sabre will run until 4 August.
- RNZ / ABC