A major search involving Australian and international personnel, police and civilians have been unable to find an army helicopter that hit the water with four soldiers on board.

There are grave fears for the lives of the crew involved in the crash, identified on Sunday as Captain Daniel Lyon, Lieutenant Maxwell Nugent, Warrant Officer Class Two Joseph Laycock and Corporal Alexander Naggs.

They were on board the Taipan helicopter when it crashed in waters near Queensland's Hamilton Island at about 12.30am on Saturday (10.30pm Friday local time).

The MRH-90 helicopter had been conducting joint military training as a part of Exercise Talisman Sabre.

Australian Army chief Simon Stuart said the men were from the 6th Aviation Regiment based at Holsworthy Barracks in Sydney.

"They're part of a really tight team, a very highly professional, highly skilled aviation unit," he told reporters on Sunday.

"I couldn't be more proud of them - as professionals, as soldiers and as people."

Some debris from the stricken helicopter was found on Saturday, but the main body of the aircraft is yet to be recovered.

Specialist navy divers on Sunday joined Queensland police and crews from the HMAS Brisbane, HMAS Adelaide and USS Miguel Keith in their search for the missing Taipan.

Lieutenant General Greg Bilton said the Whitsunday region was known for its strong currents, but conditions on Sunday have been moderate.

"There's some challenge, but it's not insurmountable," he told reporters in Townsville.

"I'm confident we've got the range of capabilities we need to be able to find the fuselage and our four mates."

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An exclusion zone remains in place in waters south of Hamilton Island, from the southern tip of Long Island, east to Perseverance Island, south to Cole Island and west to the mainland at Round Head.

Members of the public who find crash material have also been urged to contact investigators.

Prime Minister Anthony Albanese thanked all those involved in the search, saying the incident was a stark reminder that there were "no safe or easy days for those who serve in our country's name".

"On behalf of our nation, our thoughts and prayers are with the families, friends and colleagues of those who are missing," he told reporters on Sunday.

Forty-seven MRH-90 helicopters have been grounded until further notice, although details of what might have led to Friday's crash have not been revealed.

It is the second time an Australian MRH-90 has been involved in an emergency this year after a Taipan ditched into waters off the NSW south coast in March.

The helicopter has earned a reputation as unreliable in recent years, with malfunctions and technical issues forcing several earlier groundings of the fleet.

Nationals leader David Littleproud called for an "open and transparent" inquiry into the incident, saying the defence force should have the best tools available.

Defence Force Chief General Angus Campbell said the focus at this stage should be on the missing men and their families.

"In terms of the aircraft, there will be an investigation as there always is in these circumstances, and we will look to that to understand what has occurred here," he told reporters.

The Talisman Sabre training operation involves defence forces from Australia, the United States and other allies.

The joint exercises, which are mostly being held in regional Queensland, resumed late on Saturday in the Northern Territory and West Australia after an initial pause following the accident.