It depends on whether you are an Australian tax resident. See ato.gov for explanation. If you are tax resident in Australia then then you need to declare the gross income from Mali (what you recieve + tax paid in Mali) but you will be allowed a deduction for any tax paid in Mali on the amount up to the amount of Australian Tax that would be payable. If the tax in MAli is higher than you would pay in Australia then it would effectively be untaxed in Australia. This is the normal arrangement but this can alter depending on whether there is a tax treaty with Mali - somehow doubt it.
