Food aid for hundreds of thousands of Sudanese refugees in Chad, some of whom are close to starvation, will be suspended next month without more funding, the World Food Programme (WFP) said on Tuesday.

Since conflict broke out in Sudan nearly a year ago, more than half a million Sudanese refugees have fled to Chad across the long desert border and the country is now one of Africa's main refugee hot spots with more than 1 million in total.

But the WFP says it is struggling to feed them all and many are already skipping meals. Nearly half of Sudanese refugee children under five-years-old are suffering from severe anaemia.

"We've already cut our operations in ways that would have been unthinkable just a few years ago, leaving hungry people close to starvation," said Pierre Honnorat, WFP's Representative and Country Director in Chad. "We need donors to prevent the situation from becoming an all-out catastrophe."

A supply route from Chad into Sudan's Darfur, where hunger is worsening, is also at risk due to funding shortages, WFP said.

With more resources, WFP would be able to position food stocks ahead of the rainy season when some refugee populations in Chad get cut off from supplies by muddy rivers. The agency is urgently calling for $242 million to ensure ongoing support for the next six months.