The Australian Maritime Safety Authority is to conduct a probe into the sinking of the ferry MV Rabaul Queen off the coast of Papua New Guinea eleven days ago.
The latest estimates by the Morobe provincial disaster authority put the toll of those missing as a result of the sinking at 327.
PNG's Prime Minister Peter O'Neill says his government chose Australian investigators because of their experience.
He told the Post courier newspaper that local people cannot be engaged because they will be subjected to the investigation too.
Mr O'Neill says those found to be negligent in this disaster will face the law.
He says the government would also consider asking Japan for help in bringing the wreckage to the surface, after it sank in water more than a kilometre deep.