The United States Marine Corps is searching for missing crew after a military plane crashed off the coast of Shoalwater Bay in Queensland.
Ships, small boats and aircraft from the 31st Marine Expeditionary Unite and Bonhomme Richard Expeditionary Strike Group are conducting search and rescue operations after a "mishap" officials said in a statement posted online on Saturday night.
The aircraft is an MV-22 Osprey, a propeller-powered plane capable of vertical take-off from the deck of an aircraft carrier.
Three members of the crew are still missing while 23 have been recovered safely, Fox News reported.
The Minister for Defence Marise Payne said she had been advised of the crash.
"I can confirm no Australian Defence Force personnel were on board the aircraft," she said in a statement.
Senator Payne said she had briefed Prime Minister Malcolm Turnbull and spoken with US Defense Secretary James Mattis to offer Australia's support.
"Our thoughts are with the crew and families affected," she said.
The Osprey aircraft were in Australia for Operation Talisman Sabre, which saw defence forces from the United States and Australia conduct training exercises off the Queensland Coast.
The planes took a highly publicised role in the exercises but have a chequered safety record.
Since the beginning of the Osprey's testing phase in 1991, there have been 39 fatalities and crashes in conflict zones.