South Sudan hunger crisis 'to affect four million'
Some four million people in South Sudan are likely to face critical food shortages next month, British aid agencies have warned.
But the Disasters Emergency Committee says the cost of mounting an appeal to pay for aid might outweigh donations.
South Sudan's president has already warned of "one of worst famines ever".
More than a million people have fled their homes since fighting erupted between different factions of South Sudan's ruling party last December.
Thousands have now died in the conflict that started as a political dispute between South Sudan President Salva Kiir and Riek Machar, his sacked deputy, but escalated into ethnic violence.
'Slip into famine'
The Disasters Emergency Committee (DEC) - which brings together 13 UK charities to deal with international crises - says it currently has less than half of the money it needs to "prevent the growing food crisis in South Sudan from turning into a catastrophe".
"If the conflict in South Sudan continues, and more aid cannot be delivered, then by August it is likely that some localised areas of South Sudan will slip into famine," the DEC says in its report, citing international food crisis experts.
The committee says the same experts helped predict the seriousness of the East Africa food crisis in 2011, which led to the first famine of the 21st Century in Somalia.
It predicts that responsive emergency work would cost £113m ($194m), but to date they have only received £56m.
"We are very concerned... that despite some excellent news coverage of the situation, public awareness of the crisis in the UK remains very low, making a successful appeal extremely difficult," said DEC head Saleh Saeed.
Analysis - Mark Doyle, BBC international development correspondent
Journalists call dramatic news stories "sexy". And predicting a famine - however certain the aid agencies are about it - will always be less sexy than the real thing.
The financing of humanitarian work depends to a large extent on media coverage - from the coins put in charity boxes to the much larger sums given by governments.
In this case the agency experts have even put dates on the coming hunger in South Sudan - August to November.
It will be interesting to see how much impact the prediction makes.
It didn't work in late 2010 when the United Nations and others sounded the alarm about an impending famine in Somalia and elsewhere in the Horn of Africa.
The warning bells were more or less ignored and in 2011 the worst hunger crisis this century has seen so far duly took place.
That was sexy. We covered that.
Months of fighting in South Sudan has prevented farmers from planting or harvesting crops, causing food shortages nationwide.
Last month, South Sudan, which gained independence from Sudan in 2011, topped the list of fragile states in this year's index released by The Fund for Peace, a leading US-based research institute.
According to the internationally accepted IPC classification, at least the first three of these conditions must occur:
- at least 20% of the total population in a given area are on the brink of starvation due to lack of food
- acute malnutrition rates are greater than 30% of the population
- Two deaths per 10,000 people per day
- A pandemic illness
- Access to less than four litres of water a day
- Large-scale displacement
- Civil strife
- Complete loss of assets and source of income