Firstly, the ombudsman is established by legislation and he is appointed for a seven-year term and that's signed off by the Governor General.
The ombudsman, in terms of deputy ministers--or secretaries, as we say in Australia--is taken to be the equivalent of a permanent head of a department, and in that sense he reports to the Prime Minister. However, in the legislative sense, he has the ability under the legislation to table the reports he produces in Parliament. And indeed, the legislation mandates that the Prime Minister will table the annual report in Parliament within 15 sitting days of its receipt.
The best way to characterize it is that for administrative purposes the ombudsman reports to the Prime Minister, but in terms of the function of the office and the production of reports, they're produced publicly and laid before Parliament.