(Reuters) – The number of child soldiers in Central African Republic has more than doubled to as many as 6,000 in recent months as self-defense militia have sprung up to counter waves of attacks by former rebels, the United Nations said on Friday. World powers, led by France, are scrambling to contain a crisis that Paris and U.N. officials have warned could lead to genocide in Central African Republic, which slipped into chaos after rebels ousted the president in March. Some 400,000 people have fled their homes since the uprising and the tit-for-tat killings that followed.