An investigation has begun into the death of an Australian sailor in Oman during shore leave.
The sailor was a crew member of HMAS Darwin, a long-range guided missile frigate that's been involved in large drug seizures off the African coast as part of Operation Manitou which oversees counter-terrorism and maritime security operations.
The Darwin had stopped in the port of Muscat and some crew were on onshore when the sailer was found unconscious.
"Despite medical treatment, the sailor could not be revived," defence said on Thursday.
The Australian Defence Force's investigative service is working with local authorities looking into the death.
"Defence extends its deepest sympathies to the sailor's family and friends," defence said, adding it would offer no more details for now.
Earlier this month the Darwin took part in an operation that netted almost a tonne of heroin worth close to $1 billion after three boats were intercepted off the African coast.
The Darwin's home port is Fleet Base East at Woolloomooloo, within sight of the Sydney Opera House.
It carries about 200 crew and officers.
Later, the ABC reported the sailor's death was believed to have been linked to the ingestion of body building supplements bought locally.