The Group of 20 nations must agree coordinated action to ease worries about food prices as they account for most of the production of the crops at the centre of concern, the head of the U.N.'s foood agency said on Monday.

U.N. Food and Agriculture Organisation Director-General Jose Graziano Da Silva said he would not characterise the current food price rise as a crisis, but it could reach that level if harvests in the southern hemisphere were disappointing.

"We need coordinated action and I believe that the G20 is responsible enough for this action," da Silva told a news conference during a conference on water in the Swedish capital.

Speaking to Reuters, he said any coordination should involve avoiding unilateral export bans and encouraging subsitution of foods, for instance the eating of beans in Latin American and of casava in Africa.

He noted that the between 85 and 95 percent of the crops most affected by the price rises, wheat and corn, were produced by the G20 countries.

He said that even if wheat prices rose 10 to 20 percent that did not mean bread prices would rise by the same amount.

Senior figures from G20 countries will discuss the alarm bells raised by the food price rises and how to combat volatility this week, but any decisions are unlikely before a mid-September report on grain supply, officials have said.

Da Silva noted that the current food price rises were not as serious as in 2007/08, when there were violent protests in countries including Egypt, Cameroon and Haiti.

"There is no crisis," he told Reuters. "This kind of panic buying is what we need to avoid at the moment."

The third price surge in four years has come after drought in the United states and poor crops from Russia and the Black Sea bread basket region.