Export commodity prices lurched lower last month, ANZ's commodity price index recording its steepest drop for more than two years.
In world price terms the ANZ index fell 4.5 per cent to an 18-month low.
The exchange rate provided almost no offset. In New Zealand dollar terms the index fell 4 per cent to a 2 low, 21 per cent below its peak in March last year.
The decline was broad-based, with 12 of the commodities in the index declining while only two (wood pulp and pelts) rose.
"The price of sheepmeat recorded the largest decrease in April, falling 12 per cent from a month earlier, to an 18-month low," ANZ economist Steve Edwards said.