AUSTRALIANS are being told to brace for much higher interest rates - the OECD predicts at least four more rises, and most likely five, in the year ahead.

The organisation's Economic Outlook, which was released in Paris yesterday, predicts the Reserve Bank will push up its cash rate from its present 4.5 per cent to 5.1 per cent by December and then 5.7 per cent by next June.

Australia's cash rate at the time would be one of the world's highest, exceeded in the the OECD by only Turkey, Poland, Mexico and Iceland.

The prediction is sharply at odds with that of Australian financial markets, which have priced in a tightening of only 0.25 percentage points in the year ahead.