North Korea's production of staple foods has increased for the third year running, but mothers and babies still lack sufficient vitamins, fat and protein, leaving many children stunted, the World Food Program's North Korean representative said Thursday. Dierk Stegen said the government has focused on producing cereals, but that it needs a more diverse food supply. He said about 80 percent of North Korean households lack the appropriate amount of vitamins, minerals, fats and proteins in their diets. "The government has already strengthened all means to produce more food in the fields, but this is cereals and not real diversified food and that's what is lacking for babies and their mothers," he said in an interview in Beijing. Stegen said North Korea still has a high rate of stunted growth in children, but did not provide figures for this. Staple food production in 2013 increased about 5 percent year on year, with an estimated 5.03 million metric tons of milled cereals produced, Stegen said. There is a food deficit of 340,000 metric tons, most of which is expected to be filled by government imports. Stegen called the remaining gap of 40,000 tons "small." North Korea recently has made tentative steps to incorporate free market ideas within its rigid socialist system. Farmers on small teams have direct responsibility over their plots and can keep any surplus to sell, barter or distribute - a change from past policies that required farmers to turn all harvests over to the state. Stegen said local markets "have an effect on the nutrition and the supply of food to families," but said there were still questions over them "because it is not quite clear in how far families are profiting from these markets." The World Food Program has been providing food aid to North Korea since 1995. Stegen said that over the past two years they had seen "the best conditions ever" in terms of monitoring access. They have access "on an immediate basis" to about 18,000 institutions, including kindergartens, primary and boarding schools, to where they deliver nutritional supplies. Stegen spoke ahead of the Thursday publication in Rome of an annual North Korea crop and food security assessment report by WFP and the Food and Agriculture Organization.