Commodity prices are to remain "subdued" during the economic downturn, although crops look likely to suffer less than oil and metals, the International Monetary Fund has said.

The IMF, in a report forecasting an even worse global economic outlook than it had predicted in January, said that commodity prices would only pick up on signs of a turnaround.

"Commodity markets are now in a phase of cyclical weakness," said the fund.

"Prices are expected to remain subdued as long as global activity continues to slow."

Market squeeze delayed

Even when the economic revival does set in, commodity markets would stage only a sluggish recovery.

"Prices are unlikely to rebound quickly to the very high levels seen in 2007 or the first half of 2008," the fund said in its latest World Economic Outlook.

Spare capacity among commodity producers had "risen rapidly", and more was in the pipeline, suggesting that a squeeze on commodity markets would emerge "later and more gradually than previously assumed".

Wheat' relatively buoyant'

However, the outlook for crop prices was less bleak than for other commodities, thanks to farm cutbacks after last year's market slump.

"Farmers across the globe have reportedly reduced acreage and fertilizer use," the report said.

"At the same time stocks of key food staples, including wheat, are still at relatively low levels. These supply factors should partly offset downward pressure from weak demand during the downturn."

An economic model forecasting that oil, copper and aluminium prices could take beyond 2013 to recover to 2006-07 levels was more sanguine about wheat.

"The model predicts that wheat demand will remain relatively buoyant, suggesting that wheat prices may remain high throughout the downturn," the IMF said.