Export commodity prices fell in January to their lowest level for nearly four years.

The Reserve Bank of Australia’s (RBA) index of commodity prices was 1.5 per cent lower in the month, in foreign currency terms.

Commodities contributing most to the fall in January were coking coal and iron ore, although the prices of many agricultural commodities were down as well, the RBA said.

After the fall in January, the foreign currency index of commodity prices was down by 26 per cent from its all-time high in July 2011 and at its lowest point since April 2010, 45 months earlier.

Through the year to January the index fell by 10 per cent in foreign currency terms, although the falling exchange rate meant an annual rise of six per cent in Australian dollar terms.

The foreign currency price index is measured in terms of special drawing rights (SDRs), an average of four major currencies – the US dollar, euro, Japanese yen, and British pound.