Treasurer Wayne Swan has cancelled his attendance at the G20 Finance Ministers' meeting in Mexico on the weekend.
Mr Swan said in a statement on Thursday he had informed the meeting's host, Mexican Finance Minister Jose Antonio Meade, of his decision.
Australia's G20 Finance Deputy, Mike Callaghan, will go instead.
The move comes after Kevin Rudd announced he was resigning as foreign minister on Wednesday, sparking expectations he will challenge Prime Minister Julia Gillard for the top job early next week.
Mr Swan was tipped to urge nations at the Mexico talks to build a 'global firewall' in the form of an adequately-resourced International Monetary Fund (IMF), alongside a strengthened European firewall to boost confidence and prevent contagion spreading to the rest of world.
'I look forward to meeting again with my G20 colleagues at the IMF and World Bank Spring Meetings in April,' he said.
