The incident took place when the aircraft was participating in a night-time training activity between the Australian and US military off Lindeman Island on Friday.

"Four crew were on board the aircraft at the time of the incident and are currently missing," read a statement issued by the Australian Defence website.

Military and civilian search and rescue aircraft and watercraft are currently conducting search and rescue operations at the incident site.

"At this time Defence’s priority is supporting our ADF members and their families. Families of affected personnel have been notified," read the statement.