EU and US envoys have warned South Sudan's warring factions that famine is looming because they continue to ignore a ceasefire. East African states have agreed to deploy troops as monitors.
A summit of east African leaders in Addis Ababa was told on Thursday that South Sudan faces famine if warring factions continue to flout a ceasefire arrangement.
US envoy Donald Booth said the failure of a ceasefire bid in January had since led to thousands of additional deaths, with South Sudan "facing a possible famine."
EU envoy Alexander Rondos added: "If things continue as they are, the specter of famine looms."
Rilvaries become open warfare
Rivalries between President Salva Kiir and sacked Vice President Riek Machar turned into open warfare between their forces in mid-December.
That stopped the planting of crucial crops. Stores of the UN's World Food Program were ransacked.
Over 930,000 civilians fled their homes, including a quarter of a million sheltering in neighboring countries and some 75,000 crowded into UN peacekeeping bases.
Factions 'not serious'
The chief mediator of the east African Intergovernmental Authority on Development (IGAD), Seyoum Mesfin, said the factions were "not serious about ending the war."
Seymoun said IGAD leaders had discussed the sending of a "regional stabilization force" to be in South Sudan by mid-April.
He said the troop contributors would be Ethiopia, Kenya, Burundi and Rwanda.
IGAD has already urged the release of four opposition leaders put on trial for alleged treason by South Sudan's government earlier this week.