U.S. Secretary of State John Kerry says he is sending a special envoy to South Sudan to encourage talks between opposing factions in the world's newest country.
Kerry said late Friday Ambassador Donald Booth will go to the region immediately to help facilitate talks to bring an end to the violence that erupted after President Salva Kiir, a Dinka, accused former vice president Riek Machar, a Nuer, of attempting a coup.
The U.N. Security Council has urged the two sides to bring a "swift and peaceful resolution to this crisis," warning that the political dispute could affect neighboring countries.
The U.N. said Friday at least 11 civilians and two peacekeepers were killed in an attack Thursday on Akobo - a U.N. base in South Sudan. The U.N. Mission in South Sudan (UNMISS) had initially reported a higher death toll at Akobo where U.N. helicopters evacuated remaining survivors Friday.
UNMISS says the violence erupted after some 2,000 armed youth, believed to be ethnic Nuers, surrounded the base and opened fire. The U.N. says they were apparently aiming at members of the Dinka ethnic group taking shelter at the U.N. compound. Peacekeepers said they tried to negotiate with the assailants but came under "sustained attack."
The U.N. special representative to South Sudan, Hilde Johnson, said the incident at Akobo was a "criminal act for which the responsible must be held accountable."
About 35,000 civilians are believed to have taken shelter at U.N. bases in South Sudan since unrest erupted this past week.
On Friday, U.N. Security Council President Gerard Araud said armed youth have also gathered around a camp in the town of Bor, where about 14,000 civilians are taking refuge.
"Around the camp, there is heavy fighting. The last information was that a few thousand armed youth are gathering around the camp so, of course, the situation is very, very unstable there."
A U.N. Security Council statement also reported attacks on oil installations in South Sudan, with a "heavy loss of life" among oil workers.
South Sudan's government says violence in the capital, Juba, has killed at least 500 people this past week.
The Security Council president said Friday, however, that President Kiir and Machar have agreed to "unconditional dialogue."
Machar is a longtime political rival of President Kiir. The president fired him as his deputy in July, and Machar has since called for Mr. Kiir's removal from office.
Mediators from East African countries held talks with President Kiir about the spiraling unrest. Somali Foreign minister Fowzia Yusuf Adam, who was part of the group, told VOA the meeting was productive.
The mediators are with the Intergovernmental Authority on Development. The East African bloc was instrumental in mediating a 2005 agreement that ended a civil war between Sudan and rebels in the south who ultimately succeeded in winning their independence six years later.