“The crisis is a speculative attack and it will last,” said Jose Graziano, FAO regional representative for Latin America and the Caribbean.

Across the globe foods from bread to milk have become more expensive and in some countries helped fuel inflation. High prices for rice, beans and other food staples provoked food riots in Haiti.

“The lack of confidence in the US dollar has led investment funds to look for higher returns in commodities, first metals and then foods,” said Mr Graziano.

Investors have speculated in commodities including wheat, corn and rice because stocks in recent years have been drawn down by rising demand in emerging markets and supply shortages due to adverse climate in key producer nations.

According to Brazilian farm experts, stocks of some food crops have fallen to their lowest levels in three decades.

Brazil will host an FAO conference next week, which will focus on food shortages in Haiti, biofuels and small farms. Brazil is one of the world's leading food exporters.

In next week's meeting, the FAO will propose initiatives to help combat the current global food shortage, including incentives for small farmers.