GENEVA (Reuters) - Children are starving to death in Central African Republic because violence has forced aid workers to pull out, the United Nations humanitarian coordinator for the country said on Tuesday. Four years after a conflict began between Muslim Seleka rebels and Christian  anti-balaka  militias, Central African Republic had seemed calm in the early part of the year. But violence has flared since May, turning the southeast into a virtual no-go area.  There is no humanitarian assistance there. It s not even half, it s nothing, because it was just not possible for humanitarians to stay there,  coordinator Najat Rochdi said.  We started already seeing children dying from severe malnutrition.   Lack of funds had already forced aid workers to halve food aid and in some places stop it completely, despite widespread malnutrition in children under five-years-old.   What I heard -  but we have not been able to confirm it   is that so far we had 10 kids who died from malnutrition. But as long as we don t have humanitarians going there, it s very difficult for us to confirm that,  Rochdi said.  The violence is often ethnically based and tinged with suspicions of witchcraft. The latest U.N. humanitarian report said four children had been abducted and killed in the town of Bambari, their bodies found with their organs removed. In the town of Kembe, about 40 people were reportedly killed or wounded in a clash between armed groups on Oct. 10, it said. The number of displaced people has jumped by 50 percent to 600,000 this year, in addition to 500,000 who have fled into neighboring countries. Rochdi said 400,000 children were not going to school.  Overcrowded camps averaging 30,000 displaced people are fertile recruiting grounds for armed groups, so the United Nations is trying to clear out weapons and fighters and get people back home wherever possible. The U.N. peacekeeping force is only 11,600 strong, in a country the size of France and Belgium combined, and the government is struggling to create an army that can hold territory against marauding gunmen.  The United States and Uganda withdrew their forces after declaring victory in April against the Lord s Resistance Army (LRA), a marauding gang notorious for abducting and recruiting child soldiers.   Rochdi said their withdrawal  left a vacuum  and LRA attacks had continued sporadically.  