Price growth for Australia's exports slowed in the third quarter as the demand from Asia shows signs of wavering, leading one commentator to predict prices will peak within the next few quarters.

The price of Australia's exports rose by 4 per cent in the third quarter, slowing from 6 per cent growth in the second quarter, helped by stronger prices for coal and natural gas, the Australian Bureau of Statistics said. The market had expected growth of only 3.6 per cent.

"Everyone is waiting for this thing to peak but the peak keeps getting pushed out further," said JP Morgan economist Ben Jarman. "We do expect it to come down from here."

"With commodity prices and global growth looking a bit softer, we're not going to see the kind of results we have seen over the past couple of quarters."

Strong commodities prices and solid demand for them from China and other Asian customers have underpinned Australia's economic growth through a period in which other developed economies have struggled in the aftermath of the global financial crisis. In the quarter, natural and refined gas prices rose by nearly 25 per cent, while coal rose 9.3 per cent, the ABS said.

Signs are emerging, however, that commodities prices are weakening, with iron ore prices are now down by 17 per cent since early September. Fortescue Metals Group flagged weaker demand for iron ore from China. The Reserve Bank in their October meeting minutes estimated that exchange-traded base metals prices have fallen by between 15 and 25 per cent over the past two months.

Prices on imports fell from 0.8 per cent in the previous quarter to no change in the three months to the end of September, exceeding analysts' expectations that import prices would rise 0.5 per cent in the quarter. Import prices fell because of a 3.8 per cent fall in fuel costs in the quarter, ABS data show.

"The Reserve Bank continue to predict that we are near the peak for the terms-of-trade but that peak continues to elude," Roland Randall, senior Strategist at TD Securities, said.

Australia's terms of trade, or the price of a country's exports relative to imports, are at 100-plus year highs, he said.

"The fresh gains in the September quarter will have been bigger than the market was expecting prior to this release."

"The very large nominal income inflows into the Australian economy that this implies is a key factor underlying RBA’s preference to leave rates unchanged."This provides us with additional confidence that the RBA will remain on hold at its next meeting in November."