More than 70,000 South Sudanese are staying inside United Nations camps for safety as sporadic outbreaks of violence continue despite a ceasefire deal signed last week.

In Malakal, capital of the oil-producing Unity state where war crimes have been reported by one monitoring group, there are 27,000 people sheltering at a U.N. base.

Peter Tap, one of the internally displaced South Sudanese, said he was "totally afraid to go back to Malakal because of the people in uniform."

Valerie Amos, the U.N.'s top humanitarian official, described the situation in Malakal as "unbelievably dire circumstances."

Malakal, which is now controlled by government forces, has been intensely fought over and there are fears the rebels could attempt to take it back if the truce doesn't hold.