The chopper had been taking part in the large-scale Talisman Sabre exercise, which brings together 30,000 military personnel from Australia, the United States and several other nations.

It plunged into the water near the Whitsunday Islands while taking part in a nighttime operation.

"There was a catastrophic impact, and that forms part of why we are now transferring this from an activity of search and rescue to one of recovery," Marles told reporters.

Militaries from at least three nations had joined police in looking for the crew of the MRH-90 Taipan, which went down late Friday night in subtropical waters off the northeast coast of Australia.

Chief of Defence Angus Campbell said authorities would be doing everything they could to find the bodies and recover the wreckage.

"This effort will continue," he said.

"We'll be bringing our mates home to their families and to their regiments."