Foreign aid is not a legitimate role for government. All of the money that the Australian Government has is collected from taxation - it is the hard earned product of the lives of Australian citizens that has been forcibly extracted from them. The only moral roles for government is the protection of its citizens from force and fraud from outside, and from within, its boundaries. Beyond the infrastructure that must exist to fulfill these duties, governments are immorally violating the liberty of their citizens.
Hence, the confiscation of wealth from Australian citizens (taxation) and its redistribution to blighted peoples (foreign aid) is immoral. Bureaucrats may feel a warm glow as they redistribute the wealth that you have produced with your life and your effort, but they have produced nothing and "generosity" costs them not a cent.
Consider Ayn Rand's quote: " What is the basic, the essential, the crucial principle that differentiates freedom from slavery? It is the principle of voluntary action versus physical coercion or compulsion."
So, give as much as you like - voluntarily - but let's keep the government out of our pockets when it comes to being "compassionate". Have you ever noticed how generous people are when someone else is footing the bill?