When the Australian government issues debt it logically

increases the assets that are held by the non-government sector $-for-$.
reduces the capacity of the private sector to borrow from banks because they use their deposits to buy the bonds.
has no impact on the overall holdings of assets held by the non-government sector $-for-$.

Answer: has no impact on the overall holdings of assets held by the non-government sector $-for-$.

Please read Will we really pay higher interest rates? for further material or post a comment if you want further explanation.