BOR, Sudan South Sudan could face famine following low rainfall and a surge in tribal conflicts, the United Nations children's agency UNICEF said on Sunday.
U.N. officials earlier this year said at least 1.2 million people in the underdeveloped region could be left without enough food after a poor start to the rainy season.
On Sunday senior UNICEF staff said there were now fears of an even greater emergency after poor rainfall at the end of the rainy season in October and the beginning of November.
"Here the crisis is going to hit very hard, we're just seeing the beginning of it at the moment," UNICEF's deputy executive director Hilde Johnson told journalists on a visit to the south's oil-producing Jonglei state.
"If we are not able to handle the situation well ... we can expect very, very significant levels (of hunger) which can border on the red flag emergency which becomes a famine," she said.
The latest low rain levels could hit the south's next main harvest, expected early next year, said Johnson.
She added an increase in tribal fighting had driven many families away from their homes and sparse crops, leaving them even more vulnerable.
Johnson and other UNICEF officials visited a therapeutic feeding center in Bor, the capital of Jonglei, where babies with swollen bellies and clearly protruding ribs and backbones were fed a fortified peanut paste.
About 2,000 people are thought to have died in a surge of tribal clashes this year in the south, particularly around neighboring Jonglei and Upper Nile states.
Upper Nile governor Gatluak Deng Garang, told reporters on the trip tensions were mounting again in the area on news that members of the Lou Nuer tribe were planning to enter the lush Sobat river area that belongs to their long-term enemies, the Jikany Nuer.
"If they come with their arms there will be another conflict," he said.
(Reporting by Skye Wheeler, editing by Andrew Heavens)