The United Nations has warned that 17 million Yemenis will be in famine unless the world sends urgent humanitarian help. <br/><br/>UN Secretary General Antonio Guterres issued a call to action yesterday at the aid conference held in Geneva where donor countries pledged almost 1.1 billion dollars. <br/><br/>But, UN said, the amount is half of what is needed to combat what it is calling the world's largest hunger crisis. More than two million children are acutely malnourished in Yemen. <br/><br/>Aid workers say, almost half a million of them are suffering from severe acute malnutrition which is a life-threatening condition.