The Australian dollar is within striking distance of a 17-year low following an emergency $US700 billion bond buying bombshell from the US Federal Reserve, and coming on the heels of the worst week for the currency against the greenback since the global financial crisis.

On Monday, the Australian dollar weakened further, dropping as much as 1.7 per cent to US60.97¢, less than 2 per cent off its 2003 levels.