The United Nations says it faces a $4.3 billion shortfall in helping the 50 million people worldwide in need of emergency food, shelter and other humanitarian aid.

Valerie Amos, the U.N.'s top humanitarian and emergency relief official, says $7.9 billion is needed this year by the U.N. and hundreds of other aid organizations to help those suffering from disasters, drought and violence in 31 nations.

She says only $3.6 billion has been received so far.

Amos said Wednesday the conflicts in Libya and Ivory Coast, the Horn of Africa and Yemen and South Sudan are creating a need for far more money.

She says it is particularly hard to get donors to pay for aid in West Africa, Zimbabwe, Djibouti and Niger.