The United Nations says a South Sudanese government offensive in the Jonglei region has displaced roughly 100,000 civilians, causing aid workers to relocate from an area that has dire humanitarian problems.

A report from the U.N's office of humanitarian affairs said that fighting in the Waat and Walgak areas last week caused scores of thousands of civilians to flee, as well as 60 aid workers.

The U.N. warned the government offensive may exacerbate food insecurity in the Jonglei region, which has some areas that are on the brink of famine. Food drops in one area of Jonglei have been suspended, the U.N. said.

Famine was declared in two countries of South Sudan this February, but aid workers have been blocked from delivering food aid by government and rebel forces.