The US is evacuating non-emergency personnel from oil-rich South Sudan amid concerns that Africa’s youngest nation is again on the precipice of civil war.

On Friday, a South Sudanese general and dozens of soldiers were killed when a U.N. helicopter trying to evacuate them from Nasir came under attack, the government said.

UN helicopter came under fire while trying to evacuate soldiers, leaving at least 27 people dead - Anadolu Ajansı

A crew member was killed and two others were injured when a United Nations helicopter on an evacuation mission in a remote part of South Sudan was attacked.

Juba tense after arrest of opposition politicians, army generals COVER STORY | THE INDEPENDENT & AGENCIES | The political situation in South Sudan’s capital, Juba, is tense following the arrest of politicians and to army generals aligned with First Vice President Riek Machar.

The Intergovernmental Authority on Development (IGAD), an eight-member regional bloc, will convene an extraordinary summit

South Sudanese forces have arrested the petroleum minister and several senior military officials allied with First Vice President Riek Machar, Machar's spokesperson said on Wednesday, jeopardising a peace deal that ended a five-year civil war.

The aircraft came under fire as it tried to rescue wounded soldiers, the United Nations said. The attack came amid fears that a critical power-sharing deal was at risk of collapse, risking all-out civil war.

Increased violence and political friction in South Sudan threaten its fragile peace process, a United Nations rights body said on Saturday, days after the arrests of several officials allied to the country's vice president.