South Sudan, the world's newest country, is threatened by rapidly escalating ethnic violence, as officials said on Thursday that the government no longer controls the capital of its largest and most populous state.
President Salva Kiir's earlier claim that an attempted coup had triggered the ongoing violence was false, said a ruling party official. Instead the violence erupted on Sunday when the presidential guard attempted to disarm fellow guard members who belong to the Nuer ethnic group, said Choul Laam, chief of staff for the secretary general of the ruling Sudan People's Liberation Movement.
Those who tried to do the disarming were members of Kiir's majority Dinka tribe, Laam told reporters in Nairobi.
"The situation in South Sudan can be best described as tense and fragile. If it is not contained it could lead to ethnic cleansing," Laam warned.
The South Sudan government said the violence has already killed up to 500 people. Juba, the capital, was reported calm on Wednesday and Thursday, but clashes were reported in Jonglei state.
Human Rights Watch said on Thursday that South Sudanese soldiers fired indiscriminately in highly populated areas of Juba and targeted people for their ethnicity during recent fighting in the city.
Citing witnesses and victims of the violence, the group reported that "soldiers specifically targeted people from the Nuer ethnic group." People were questioned about their ethnicity and "deliberately shot" if they were Nuer. In some cases, the group added, the Dinka may have been targeted by Nuer soldiers.
The International Crisis Group also said on Wednesday that armed groups in Juba "targeted civilians based on ethnicity."
As the unrest appeared to escalate, the United States has urged its citizens to depart South Sudan immediately.
Philip Aguer, the South Sudanese military spokesman, said military authorities in Bor, the capital of Jonglei state, were not answering their phones Thursday, leading the central government to believe they had defected.
"We lost control of Bor to the rebellion," Aguer said.
He said there were reported gunfights in Bor overnight as renegade officers tried to wrest control of the town from loyalist forces. At least 19 civilians had been killed there, said Martin Nesirky, a spokesman for the UN secretary-general's office, citing figures from the South Sudan Red Cross.
Kiir had announced to the nation that the violence was started by an attempted coup led by ousted vice-president Riek Machar. Machar, a Nuer, has denied he was behind any coup attempt. Jodi Jongole Boyoris, a lawmaker from Jonglei, said soldiers loyal to Machar now control Bor.
Machar, an influential politician who is a hero of the brutal war of independence against Sudan, is Kiir's rival for top leadership of the ruling Sudan People's Liberation Movement party. Tensions had been mounting since Kiir fired Machar as his deputy in July. Machar, the deputy chairman of the ruling party, later said he would contest the presidency in 2015.
The think tank Eurasia Group said Kiir's firing of Machar in July alienated the "long-aggrieved Nuer" in a country with "a factionalised military and a history of violent ethnic rivalries."
United Nations chief Ban Ki-moon told reporters Wednesday that South Sudan was experiencing a political crisis that "urgently needs to be dealt with through political dialogue." Ban said he urged Kiir "to resume dialogue with the political opposition."
South Sudan has been plagued by ethnic violence since it peacefully broke away from Sudan in 2011 after decades of civil war.