Defense Minister Richard Marles told reporters on Saturday that four Australian army helicopter crew members were missing after their chopper crashed late on Friday. 

Multinational military exercises, including a large US contingent, called Operation Talisman Sabre have been halted to allow a full focus on the search.

"Defense exercises, which are so necessary for the readiness of our defense force, are serious. They carry risk," Marles told reporters in Brisbane. 

Australian police said they recovered helicopter debris, but after a full day of rescue operations, there was still no sign of the four missing crew members.

"We have located a number of items of debris that would appear to be from the missing helicopter," said Queensland Police Superintendent Douglas McDonald. "At this time it remains a search and rescue operation," he added. 

What do we know about the crash? 

Marles said the chopper ditched late on Friday evening near Hamilton Island, off the coast of Queensland in northeastern Australia. The helicopter was part of a two-helicopter mission, he said, meaning a search and rescue mission could be launched immediately.

"As we speak to you now, the four air crew are yet to be found, the search and rescue continues," Marles said. "The families of the four air crew have been notified of this incident."

The helicopter that crashed was an MRH-90 Taipan, a medium-sized multi-role helicopter capable of carrying several crew and manufactured in Europe. It's the second crash this year involving an Australian Taipan; one crashed in March off New South Wales, but all 10 crew were rescued.

Marles said the government's hopes and thoughts were "very much with" the air crew and their families, as well as the rescue teams. 

The chief of the Australian Defence Force, Angus Campbell, appeared alongside Marles and told reporters: "Our focus at the moment is finding our people, and supporting their families and the rest of our team. This is a terrible moment." 

US visitors Blinken, Austin offer condolences

News of the crash broke on the morning of more talks between senior members of the US and Australian governments, with US Defense Secretary Lloyd Austin and Secretary of State Antony Blinken both in Brisbane on Saturday. 

"It's always tough when you have accidents in training, but the reason that 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 kind of crisis," Austin said.

He added that while troops often made their jobs "look easy" when in action, rigorous preparation with an element of risk was "what it takes" to enable them to do this. 

Blinken said, "We're so grateful to them for their dedication, for their service, for everything they've been doing to stand up for the freedom that we share and that is what unites us more than anything else." 

msh/sri (AFP, AP, Reuters)