About 800 defence and emergency services personnel in Australia have joined the search for four crew members after a helicopter involved in a multi-national military exercise crashed off Queensland's coast on Friday night.

Authorities say wreckage found off the Queensland coast will form part of the crash investigation and that specialist divers will scour the area on Sunday morning.

By late on Saturday afternoon, none of the crew members of the MRH90, also known as a Taipan, had been found.

Families of the missing people have been notified and the Australian Army has paused all MRH90 fleet activity.

Previously, the New Zealand Defence Force, which was also due to take part in the military exercise, confirmed none of its members were in the helicopter which crashed.

The chopper had been involved in training as part of Exercise Talisman Sabre when it crashed in waters near Lindeman Island, south of Hamilton Island.

"We have located a number of items of debris that would appear to be from the missing helicopter," Queensland Police Service (QPS) Acting Assistant Commissioner Douglas McDonald said.

"We have a barge working up there, we also have police working around those islands, patrolling beaches.

"If any members of the community are on those beaches, and come across anything they might think is debris related to this particular incident, [please] contact police immediately and don't touch the items."

Talisman Sabre exercise director Brigadier Damian Hill said as of Saturday evening HMAS Brisbane was at the scene, with HMAS Adelaide arriving later on Saturday night and HMAS Huon due to arrive early on Sunday.

"HMAS Huon has some of our more experienced divers should we need to look under the water for wreckage as the search and rescue continues," he said.

Hill said the water was "quite deep" in the area being searched.

"Upwards of 800" people were assisting with the search, he said.

They included the Australian and US defence forces, both federal and Queensland emergency services, air and maritime assets, RAAF, US Navy patrol aircraft, Canadian helicopters, Queensland and federal agency fixed-wing aircraft, and Queensland emergency vessels.

'Our thoughts are with the crew and their families'

Earlier on Saturday, Defence chief Angus Campbell described the crash as a "terrible moment".

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"Our focus at the moment is finding our people and supporting their families and the rest of our team," General Campbell said.

"I really deeply appreciate the assistance that has been provided by a variety of civil agencies - the Queensland Police, the Australian Maritime Safety Agency, and the public as well as our US allies."

Speaking in Brisbane on Saturday morning, Defence Minister Richard Marles said a second chopper that had been flying with the Taipan immediately began a search and rescue operation.

"Our hopes and our thoughts are very much with the aircrew and their families," Marles said.

"Our hopes are very much with the efforts of the search and rescue crews as they go about their work right now."

US Marines and Australian soldiers have been conducting exercises together in the Whitsundays as part of Talisman Sabre.

The accident overshadowed the AUSMIN talks that Marles and Foreign Minister Penny Wong held in Brisbane with US Defence Secretary Lloyd Austin and Secretary of State Antony Blinken.

Wong opened the meeting by calling the crash a "stark reminder of the risks that men and women who serve us take, and the courage they show in serving their country".

Austin also spoke about the missing personnel, saying training accidents were "always tough".

"But the reason we train to such high standards is so that we can be successful, and we can protect lives when we are called to answer any sort of crisis," Austin said.

Marles said while defence exercises were necessary, "they carry risk".

"And as we desperately hope for better news during the course of this day, we are reminded about the gravity of the act which comes with wearing our nation's uniform."

Taipan fleet grounded in 2019

While the cause of this accident is not yet clear, the tragedy will inevitably renew debate about the MRH90 Taipan fleet, which has been plagued by difficulties.

Ten Australian defence force personnel had to be rescued from the waters off the New South Wales south coast in March this year after their Taipan helicopter ditched into the water during a counterterrorism training exercise.

The entire Taipan fleet was also grounded back in 2019 in order to fix their tail rotor blades.

The ABC revealed in April that a critical software upgrade was not installed on all helicopters in the fleet.

In late 2021, the then-defence minister Peter Dutton announced that the ADF would retire the fleet a decade earlier than scheduled, replacing them with new Black Hawk and Seahawk helicopters from the United States.

- ABC, with additional reporting by RNZ