UN commission of human rights in the country says the stage is set for a repeat of the Rwandan genocide.
What is the UN saying?
The head of the UN Commission on Human Rights in South Sudan, Yasmin Sooka, finished a 10-day visit of of the African country on Thursday. Here's what she had to say.
"There is already a steady process of ethnic cleansing under way in several areas of South Sudan using starvation, gang rape and the burning of villages; everywhere we went across this country we heard villagers saying they are ready to shed blood to get their land back."
"The stage is being set for a repeat of what happened in Rwanda and the international community is under an obligation to prevent it," Sooka said, referring to Rwanda's 1994 genocide in which 800,000 people died.
What is the government of South Sudan saying?
South Sudan's President Salva Kiir, strongly denied the UN allegations.
"There's no such thing in South Sudan. There's no ethnic cleansing," Kiir said in the South African city of Johannesburg. Security guards prevented further questions.
What could happen if the allegations are proven?
A three-person commission was set up this year and is set to report back to the UN Human Rights Council next March. Similar investigations into North Korea and Eritrea ended in calls to refer the situation to the International Criminal Court in the Hague, but neither case has reached the court.
The UN rights experts repeated calls for an arms embargo, sanctions, the deployment of another 4,000 peacekeepers and the establishment of a special war crimes court.
What are the facts so far?
More than 1.1 million South Sudanese have fled the country and 1.8 million have been uprooted, most recently in the Equatorial regions, where houses are being torched and people being displaced based on ethnicity, the statement said.
The UN rights committee repeated calls for an arms embargo, sanctions, the deployment of another 4,000 peacekeepers and the establishment of a special war crimes court.
The US on Wednesday also warned of escalating violence.
"We have credible information that the South Sudanese government is currently targeting civilians in Central Equatoria and preparing for large scale attacks in the coming days or weeks," Keith Harper, the US representative at the UN Human Rights Council, said in Geneva.
"In the last two weeks, the government has mobilised at least 4,000 militia from other areas of South Sudan and is staging these fighters in Equatoria to begin conducting attacks," Harper said.