The United Nations has warned of a rapidly rising risk of mass starvation in northeast Nigeria, Somalia, South Sudan and Yemen, due to drought and conflict. <br/><br/>A UNHCR spokesman said today, some twenty million people live in hard-hit areas where harvests have failed and malnutrition rates are increasing, particularly among children. <br/><br/> He said the refugees agency is scaling up its operations but is faced with problem of severe funding shortfall.