South Sudanese gunmen have killed up to 50 civilians sheltering at a UN base. The shelter was home to at least 5,000 people who had fled four months of ethnic violence.
The US ambassador to the United Nations, Samantha Power, said several people were killed and dozens wounded on Thursday when armed civilians stormed the shelter in Bor in Jonglei state and opened fire on civilians from a rival tribe.
She said the attack had been "particularly egregious" as the perpetrators had used rocket-propelled grenades to breach the compound.
"This latest outrage against the people of South Sudan is an affront to the international community and violates fundamental principles of civilian protection," she said, adding that UN bases should be considered "inviolable."
The United Nations said the gunmen gained access by posing as protesters and asking to deliver a petition to the UNMISS (the UN peacekeeping mission.)
'Serious escalation' in violence
The UN said its peacekeepers fired warning shots to repel the "unprovoked attack" before opening fire. A ferocious gun battle then ensued before the rebels fled, it said.
Spokesman Stephane Dujarric earlier said the UN had no official figure for the number of fatalities as yet, but that two peacekeepers were among the wounded.
He condemned the attack as a "serious escalation" in ethnic violence which has plagued the world's newest nation for more than four months.
"The (UN) Secretary General reminds all parties that any attack on United Nations peacekeepers is unacceptable and constitutes a war crime," he added.
Thousands seeking refuge in camps
Thousands have been killed and more than one million people have fled their homes since fighting broke out in December between supporters of ousted vice President Riek Machar and forces loyal to President Salva Kiir.
The opposing forces hail from rival tribes, adding a dangerous ethnic element to the conflict.
An estimated 65,000 people have sought refuge at UN bases like the one in Bor.
The 5,000 civilians in the camp at the time of the attack are said to hail from the same tribe as Riek Machar, whose alleged attempt to unseat the president after he was sacked from office sparked the conflict.
Bor has been one of the most bitterly disputed regions and has swapped hands between rebel and government forces several times.
Military seeks to reclaim key oil town
Earlier this week fighters loyal to Riek Machar claimed to have gained control of Bentiu, the capital of oil-producing Unity state. They warned oil firms to leave the region within a week.
South Sudanese Information Minister Makuei has insisted that all oil fields remain under government control, but said production had stalled at facilities which were damaged in fighting.
The military said it had launched an operation to reclaim the town.
According to the UN dozens of people have died in Bentiu in recent days.
Thousands face starvation
With seemingly no end in sight to the conflict UN Secretary General Ban Ki-moon warned Wednesday that up to a million people face famine in the coming months.
This warning was repeated by the UN children's agency UNICEF on Thursday, which said more than 3.7 million people are in dire need of food aid.
"If conflict continues, and farmers miss the planting season, we will see child malnutrition on a scale never before experienced here," said South Sudan's UNICEF chief, Jonathan Veitch.
ccp/jm (AFP, AP, Reuters)