Tens of thousands of people surviving on water lilies and swamp fish after fleeing South Sudan's war may run out of food entirely when the dry season starts in January, food security experts said in a report seen by Reuters on Thursday.
The team predicted that, without help, there was a high chance of a "widespread catastrophe" in the first three months of next year.
The Integrated Food Security Phase Classification (IPC) team said after a trip to South Sudan's Unity State that said 40,000 people there were projected to be in a food security "catastrophe" and at risk of famine.
That is an increase of 10,000 since an IPC report on Oct. 22, which also said 830,000 people were in an "emergency" situation and a further 3.1 million in "crisis".
The IPC members include non-governmental organisations and U.N. agencies including the Food and Agriculture Organization and World Food Programme.
South Sudan was plunged into a civil war in December 2013 when a political crisis triggered fighting between forces loyal to President Salva Kiir and rebels allied with his former deputy Riek Machar. The conflict has reopened ethnic faultlines that pit Kiir's Dinka people against Machar's ethnic Nuer people.
Fighting intensified in May in Unity State, killing tens of thousands of head of cattle, destroying markets and crops, and displacing over 100,000 civilians, most of whom are still thought to be sheltering in the bush and in island villages, the report said.
More than 645,000 people have fled the country since December 2013 and about 200,000 have taken refuge in U.N. bases across the country.
All households were dependent on water lilies and fish from local rivers and swamps, but the water will recede from January to March, putting those households at real risk of having no food at all by early next year, the report said.
Before the conflict, local people said they had consumed three or four meals a day, including milk, meat, fish blood, sorghum, maize, sesame and groundnuts.
More violence could come with the dry season in January, and any aid delivery is very likely to draw a looting attack, the report said. An area that received WFP food aid in October, was attacked the following day and the food looted, the report said.
The U.S.-funded Famine Early Warning Systems Network said around half the population would be acutely food insecure by May 2016, with Upper Nile State in particular need of food aid.