ROME — A significantly deteriorating food security situation in Syria has left wheat flour milling facilities and bakeries in the country either no longer operating or operating at low capacity, according to a new report published by the U.N. Food and Agriculture Organization and the World Food Program. The report noted the average monthly price of wheat flour more than doubled between May 2011 and May 2013 in several locations in Syria, resulting in serious bread shortages in the country. As a result, the W.F.P. said it began distributing wheat flour this past April. The F.A.O. and the W.F.P. said there may be further declines in domestic agricultural production over the next 12 months if the present situation continues. “There is a limited window of opportunity to ensure crisis-affected families do not lose vital sources of food and income,” the two U.N. organizations said.