The visiting Norwegian Refugee Council Secretary General said they were working on plans to rehabilitate South Sudan.
Jan Egeland said the Council was investing in emergency relief and development efforts.
The Secretary General said women in some camps he visited told him that they were fed up of war and wanted to return home and rebuild their devastated areas.
UN Humanitarian Coordinator Toby Lanzer said Malakal was completely destroyed and deserted.
He said they did not see any civilian alive on the street, but found evidence of people killed inside the hospital.
The two officials made the statements on Thursday in Juba after touring the Upper Nile region and parts of Lakes State.