The UN World Food Programme says due to a shortage of funding it is having to suspend some food aid in South Sudan where more than half the population is grappling with severe food insecurity.
The crisis has been fuelled by conflict, flooding, drought and and soaring food prices exacerbated by the crisis in Ukraine.
The WFP says among those affected by the cuts will be close to 200,000 children who will no longer receive daily school meals.
It describes these as a crucial safety net that helps keep South Sudanese children in school.
“We are extremely concerned about the impact of the funding cuts on children, women and men who will not have enough to eat during the lean season,” said WFP country director Adeyinka Badejo.
“If this continues, we will face bigger and more costly problems in the future, including increased mortality, malnutrition, stunting, and disease."
The WFP is appealing for more than $400m (£330m).