The US and the European Union have taken a "criminal path" by encouraging use of food crops to produce bio-fuels and thus contributing to an "explosive rise" in global food prices, the UN Special Rapporteur on the right to food has said.

Jean Ziegler held fuel policies pursued by the US and the EU to be main causes for the current worldwide food crisis.

Last year the US used a third of its corn crop to create bio-fuels, while the European Union is planning to have 10 per cent of its need supplied by bio-fuels, he said and called for a for a five-year moratorium on the production of bio-fuels.

Ziegler also said that speculation on international markets was behind 30 per cent increase in food prices. Besides, hedge funds are also making huge profits from raw materials markets and called for new financial regulations to prevent such speculation.

The Special Rapporteur, in a press conference, warned of worsening food riots and a "horrifying" increase in deaths by starvation.

Meanwhile, speaking in Rome, a nutritionist with the UN World Food Programme (WFP), said that "global price rises mean that food is literally being taken out of the mouths of hungry children whose parents can no longer afford to feed them."

Andrew Thorne-Lyman said that even temporarily depriving children of the nutrients can leave permanent scars in terms of stunting their physical growth and intellectual potential.

Families in the developing world are "finding their buying power has been slashed by food price rises, meaning that they can buy less food or food which isn't as nutritious," he added.