The United Nations will be forced to end food distribution in Somalia unless armed groups there stop attacking U.N. staff, the World Food Programme (WFP) said on Thursday. Humanitarian workers have repeatedly been targeted during a two-year-old rebellion by Islamist insurgents that has killed more than 16,000 civilians and uprooted one million others. Four WFP staff have been killed since August last year. Peter Goossens, WFP country director for Somalia, said the U.N. agency was distributing about 57,000 metric tonnes of food to southern and central regions that he said would feed some 2.5 million people until around mid-February. "That is it basically," Goossens told a news conference in neighbouring Kenya.