LONDON — The United Nations said Friday that it had sent helicopters to rescue personnel from a base in South Sudan that came under lethal attack amid a worsening political crisis, and President Obama warned that South Sudan, the world’s youngest country, “stands at the precipice.”
The number of civilians seeking refuge in the United Nations’ other outposts there exceeds 30,000, and diplomats expressed fears about the potential for a civil war after a week of ethnic violence that has killed hundreds.
The US Embassy conducted a fifth emergency evacuation flight Friday to move Americans out of the country. British, German, and Dutch planes were also scheduled to fly out.
The United States has advised Americans to leave the country and suspended operations at its embassy in Juba, the capital.
Armed rebels were said to be in control of some of South Sudan’s oil fields Friday, raising questions of how long the country’s oil will flow and whether Sudan could enter the conflict, the Associated Press reported.
Casie Copeland, South Sudan analyst for the International Crisis Group., said armed opposition groups appeared to be in control of some oil fields in Unity state, the Associated Press said.
President Salva Kiir implored the country Friday to turn away from violence and met with foreign ministers from neighboring countries, including Kenya and Ethiopia, who flew into Juba to help calm tensions.
‘‘Those who may want to take the law into their hands, the long arm of the government will get them,’’ Kiir said, according to the government’s Twitter feed.
China, which operates oil fields near Juba, also took steps Friday to protect its nationals in the country. The China National Petroleum Corp. began what it called “the orderly evacuation of our workers,” Agence France-Presse reported.
The UN peacekeeping force in South Sudan said it had sent four helicopters to rescue personnel at its base in the town of Akobo in Jonglei State, where, it said, two Indian peacekeepers had been killed when it was attacked Thursday. India said earlier that three of its soldiers had died.
The mission said it had “received assurances from forces in charge of Akobo town that its helicopters will be permitted to land safely.” Earlier, Kieran Dwyer, a spokesman for the UN Department of Peacekeeping Operations, said communications with the base in Akobo had been lost.
At the time of the assault by unidentified attackers, the Akobo base housed 43 Indian peacekeepers, six UN police advisers, two civilians of undisclosed nationality, and about 30 South Sudanese who had sought refuge there from the fighting in the area, the United Nations said.
Earlier Friday, the mission said on Twitter that 34,000 people had taken refuge at its compounds.
The situation in South Sudan has been tense for months, but it has quickly deteriorated in the past five days since Kiir accused his former vice president, Riek Machar, of attempting a military coup, which Machar denied.