Syria's six-year conflict has caused at least $16 billion in damage to agriculture - about a third of the country's GDP - a U.N. agency said on Monday, calling for more funds to salvage local food production as millions go hungry. Fighting has led to extensive crop and livestock losses and destroyed greenhouses, veterinary clinics, irrigation systems, tractors and other assets, the U.N. Food and Agriculture Organization (FAO) said in a report - the first to provide a comprehensive assessment of the war's impact on agriculture. Food production dropped to an all-time low last year, with many farmers forced to abandon their land.