The UN's World Food Programme says the number of people needing food aid in south Sudan has quadrupled in a year to more than four million. A minister said this amounted to about half the total population.<br/><br/>The WFP says the huge surge has been caused by increasing conflict and drought. Southern Sudan is slowly recovering from a two-decade civil war with the north, and remains one of the least developed parts of the world.<br/><br/>The UN says last year, some 2,500 died in conflicts between rival communities in Southern Sudan – far more than in Darfur. Tension is escalating in Sudan before elections due in April – the first national multi-party elections in 24 years.