Last Updated Dec 22, 2013 5:20 PM EST
KAMPALA, Uganda - The United Nations Mission in South Sudan says it is relocating all non-critical staff from the capital, Juba, to Uganda amid escalating violence as the country's military battles rebel forces.
The mission said in a Twitter update Sunday that all remaining civilian staff in Bor - the Jonglei state capital that has been the scene of fierce fighting -had been evacuated to Juba.
On Saturday gunfire hit three U.S. military aircraft trying to evacuate American citizens in Bor, wounding four U.S. service members in the same region gunfire downed a U.N. helicopter on Friday.
The German military said on Saturday it had evacuated 98 people, including Germans and other nationals, from South Sudan by air to neighbouring Uganda. The German ambassador to South Sudan was among them, the Foreign Ministry in Berlin said.
The U.N. mission said earlier one of four U.N. helicopters sent to Youai, in Jonglei state, had come under small-arms fire on Friday, Reuters reports. No crew or passengers were harmed.
The latest violence in the world's newest country has killed hundreds and has world leaders concerned about war.
The U.N. chief Sunday urged South Sudan's leaders "to do everything in their power" to stop the violence.
Hundreds of people have been killed in the fighting between Dinka loyalists of President Salva Kiir and Nuer supporters of former Vice President Riek Machar, who was sacked in July and is accused by the government of trying to seize power.
President Barack Obama warned that any move to take power by military means would lead to an end of U.S. and international community support for South Sudan.
After meeting African mediators on Friday, Kiir's government said on its Twitter feed that it was willing to hold talks with any rebel group. The United States is sending an envoy to help find a negotiated solution.
South Sudan's foreign minister, Barnaba Marial Benjamin, told Reuters the government had given African mediators the go-ahead to meet Kiir's rivals.