JOHANNESBURG, South Africa — The United Nations Security Council authorized an urgent increase in peacekeeping forces for South Sudan on Tuesday in a bid to keep the world's newest country from sliding into prolonged ethnic bloodletting only two years after gaining independence.
International officials said they had found a mass grave and cited reports of several more. Tens of thousands of people were seeking shelter in or near U.N. bases. Regional analysts said the number killed in the remote, impoverished country probably was already in the thousands.
In July 2011, Sudan's mostly Christian and animist south seceded peacefully from the Arab, Muslim north after decades of civil war, creating South Sudan. Analysts cite that as a notable achievement of President Obama's first term, and the new country has been lavished with international aid and investment to help establish itself.
But South Sudan also has been plagued by corruption and ethnic tension, which burst into the open after President Salva Kiir, a member of the Dinka tribe, fired his vice president, Riek Machar, in July. Kiir accused Machar, a member of the Lou Nuer tribe, of plotting a coup.
Fighting spread this month to half of South Sudan's 10 states and threatened to shut down oil production, on which the country depends for 98% of its revenue.
Four U.S. servicemen were wounded Saturday when militias fired on military aircraft on a mission to evacuate American citizens.
More than 7,000 peacekeepers are already in South Sudan. The Security Council voted unanimously Tuesday to increase the number by more than 5,000, redeploying them from missions in other African countries such as Liberia, Ivory Coast and the Democratic Republic of Congo as soon as possible. The council also increased the size of an 800-member U.N. police force in South Sudan by more than 400.
"The world is watching, and the world is acting," U.N. Secretary-General Ban Ki-moon said.
"There is a palpable fear among civilians of both Dinka and Nuer backgrounds that they will be killed on the basis of their ethnicity," said Navi Pillay, the U.N. high commissioner for human rights. "There needs to be clear statements and clear steps from all those in positions of political and military control that human rights violations will not be tolerated, and those responsible will be brought to justice."
The U.S., Norway and Ethiopia were leading efforts to get the two sides to stop fighting and negotiate. But some U.N. officials have expressed fear that ethnic-based militias in some parts of the country are already out of control.
U.S. special envoy Donald Booth pressed Kiir for a cease-fire and peace talks during a meeting Monday, as did regional leaders of the Intergovernmental Authority on Development.
"The future of South Sudan is in jeopardy, and this moment demands urgent leadership to avoid further bloodshed and to restore stability," the U.S. ambassador to the United Nations, Samantha Power, said in a statement late Monday. Before her appointment as ambassador, Power wrote extensively about the failure to prevent genocides.
Last week she visited the Central African Republic, a neighbor of South Sudan that is being torn apart by sectarian violence, but analysts said South Sudan is a higher priority for Washington.
South Sudan's cause has been popular in Washington, in part because of the brutality of the government in Khartoum, Sudan. The civil war with the south claimed an estimated 2 million lives. Separately, Sudanese President Omar Hassan Ahmed Bashir is wanted by the International Criminal Court on charges of war crimes in the Darfur region of western Sudan.
Under an agreement in 2005, southern Sudanese were allowed to vote on independence, and established an independent country six years later. The new nation has the highest incidence of maternal death in the world, with only 1 person in 3 having access to safe drinking water and 1 in 4 able to read.
"South Sudan is a strategic priority for the U.S.," said Alex Vines of the London-based Chatham House think tank. "We are in danger of a civil war."
"There's been tremendous Western support of capacity building, security sector reform and goodwill to this new state, and that all seems to be being ripped up now by the politics in the country itself," he said.
Other analysts said Kiir had managed to avoid tough criticism from Washington despite corruption and questionable policies. He invaded Sudan last year to seize an oil production area but was forced to back down. He also halted oil production for 15 months in a dispute with Sudan over oil transit fees.
Although Kiir fired Machar in July, the power struggle started descending into widespread ethnic bloodshed only in the last 10 days. Machar denied planning a coup and demands that Kiir step down.
Both sides claim to be ready for peace talks. The main stumbling block is that Kiir is demanding that Machar come to the negotiating table with no preconditions, while Machar is insisting on the release of 10 opposition politicians before he will talk.
Pillay said U.N. officials had documented "mass extrajudicial killings, the targeting of individuals on the basis of their ethnicity and arbitrary detentions."
U.N. staff on Monday counted 14 bodies in a grave in Bentiu, in Unity state, and 20 others at a nearby river, according to news reports. The victims were reportedly members of the Sudan People's Liberation Army and were believed to be among 75 ethnic Dinka reported missing and feared dead, a spokeswoman for the Geneva-based U.N. human rights office was quoted as saying.
There were reports of at least two other mass graves near the capital, Juba, Pillay said. Many of those killed in that area were ethnic Nuers, according to local accounts.
The U.N. said 81,000 people had fled their homes in South Sudan in the last week, 45,000 of whom have sought shelter in or near U.N. bases. Thousands more are hiding in the bush for fear of being killed because of their ethnicity, according to local reports, and oil production has been shut down in several major fields.
There was intense fighting Tuesday for control of the city of Malakal in the oil-producing state of Upper Nile, local radio reported. Unity state, another oil-rich area, and Jonglei state are in the hands of rebels loyal to Machar.
The loss of control of another major oil state would be a huge blow for the government. Oil Minister Stephen Dhieu Dau told Reuters news agency Tuesday that production in Unity state had been shut down.
The oil shutdown also affects neighboring Sudan, which benefits from transit fees.
The South Sudan government said that its forces had retaken Bor, the capital of Jonglei state, and that an attack to retake Bentiu was planned soon.