The UN food agency FAO today warned of a worrying rise in food prices which will affect millions of people following unexpected shortfalls in major cereals owing to bad weather last year.Aldolreza Abbassian, an economist at the Rome-based Food and Agriculture Organisation (FAO), told AFP that the prices began to rise in August and by December had reached the highest level since the statistical index began in 1990.He however said, not all cereals are affected. While Maize and wheat prices have risen quite sharply, the cost of rice has remained at an average price since 2007.Abbassian said the situation is not as critical as in 2008, when the price of cereals reached historic levels, provoking a food crisis and riots in a number of African countries, as well as in Haiti and the Philippines.