The Australian dollar has slumped through US68¢ to its lowest point since the depth of the global financial crisis, excluding January's flash crash, tracking the tumble in the Chinese yuan to its lowest level since 2008 as trade tensions between the world's two largest economies escalate.

The People's Bank of China allowed the yuan to breach 7 against the US dollar, saying the move through the closely-watched level was due to pressures from "trade protectionism". The PBoC said it was able to keep the yuan "at a reasonable level".