Food aid to help Sudanese refugees in four neighbouring countries could end within the next couple of months without an urgent injection of new funding, a World Food Programme (WFP) official said on Tuesday, warning of rising malnutrition levels.

Over 4-million refugees have fled Sudan's more than two-year civil war to seven neighbouring countries where shelter conditions are widely viewed as inadequate due to chronic funding shortages.

"Unless new funding is secured, all refugees will face assistance cuts in the coming months," Shaun Hughes, the WFP's emergency coordinator for the Sudan regional crisis, told a Geneva press briefing, calling for $200-million over six months.

"In the case of four countries - that's the Central African Republic, Egypt, Ethiopia and Libya - WFP's operations are now so severely underfunded, that all support could cease in the coming months as resources run dry," he said, clarifying later that this could happen within two months.

Many of those fleeing are escaping from hunger hot spots in Sudan. A joint UN report said last month the country was at immediate risk of famine.

Hughes said that any reduction or end to rations would leave child refugees at a greater risk of malnutrition.

Asked why the funding had fallen, he cited reductions from donors across the board and rising humanitarian needs.

He added that the United States, which has reduced its foreign aid spending dramatically under President Donald Trump, remained its top donor for Sudan.