SYDNEY, Aug 3, 2023 (BSS/AFP) - Human remains have been found at the site where an Australian military helicopter plunged into the sea off the country's northeast coast, authorities said Thursday.

Four crew members were on board the MRH-90 Taipan helicopter when it crashed close to the Whitsunday Islands during a multinational military exercise on the night of July 28.

The army's chief of joint operations, Lieutenant General Greg Bilton, told reporters in Queensland that the remains had been found by a remotely operated underwater vehicle.

They were located about 40 metres (130 feet) below the water's surface along with wreckage from the helicopter, including parts of the cockpit.

Bilton said the debris field was "consistent with a catastrophic high impact", and that the human remains were unlikely to be identified until more wreckage was found.

Search team efforts had been hampered by strong currents and poor weather that was expected to last well into next week, he added.

Meanwhile, an investigation is underway into the cause of the crash, but search teams have yet to find the helicopter's black box.

"It's a difficult task but we will do our absolute best to find it -- the black box is critical to helping us to understand what's actually taken place," Bilton said.

All communications from the helicopter were "normal" before it crashed, he added.

Following the crash, Australia's Taipan fleet was grounded, with Defence Minister Richard Marles saying on Monday that the helicopters would not fly again until the crash investigation was completed.

The Taipans, which have had a troubled history, were already due to leave service at the end of this year, with the Australian military switching to Black Hawks.