Renegade troops loyal to South Sudan's former deputy president have taken the capital of a key oil-producing state as fighting between military factions spread across the nation Sunday, the military said.
Bentiu, the capital of oil-rich Unity state, is now controlled by a military commander loyal to former Vice President Riek Machar, said Col. Philip Aguer, the South Sudanese military spokesman.
"Bentiu is in the hands of a commander who has declared support for Machar," he said. "Bentiu is not in our hands."
The armed rebels were said to be in control of some of South Sudan's oil fields on Friday, which have historically been a target for rebel movements.
Although the country's capital, Juba, is mostly peaceful a week after a dispute among members of the presidential guard triggered violent clashes between military factions, fighting continues to spread as the central government tries to assert authority in the states of Unity and Jonglei. Bor, the capital of Jonglei, is said to be the scene of some of the fiercest clashes between government troops and rebels.
The U.N. Mission in South Sudan said in a Twitter update Sunday that all non-critical staff in Juba are being evacuated to Uganda. It said all its civilian staff in Bor had been evacuated to Juba.
The United States and other countries have been evacuating their citizens from South Sudan, as violence escalates in the world's newest country and threatens lives and oil production. Hundreds have been killed in the fighting and world leaders are concerned about full-blown civil war in a country with a history of ethnic violence and divided military loyalties.
On Saturday gunfire hit three US military aircraft trying to evacuate American citizens in Bor, wounding four US service members in the same region gunfire downed a U.N. helicopter on Friday.
Earlier this week the top military general in Bor defected with his troops, starting a rebellion that appears to be spreading to other parts of the country.
Aguer said Bor is still under the control of pro-Machar forces, disputing reports the rebels had fled as government troops advanced on Bor.
South Sudan's President Salva Kiir, an ethnic Dinka, earlier this week said an attempted coup had triggered the violence, and the blame was placed on Machar, an ethnic Nuer. But officials have since said a fight between Dinka and Nuer members of the presidential guard triggered the fighting that later spread across the East African country.
Machar's ouster from the country's No. 2 political position earlier this year had stoked ethnic tensions. Machar, who has criticized Kiir as a dictator, later said he would contest presidential elections in 2015.
U.N. Secretary-General Ban Ki-moon on Sunday urged South Sudan's leaders "to do everything in their power" to stop the violence.
Foreign ministers from neighboring countries Kenya, Ethiopia, Uganda and Djibouti are in South Sudan to try and diffuse the crisis.
South Sudan became independent in 2011 after decades of a brutal war with Sudan.