Doctors without Borders, the only organisation providing health care in the area, said its staff had mostly fled into the bush, while there were reports of damage on the outskirts of town, including huts being torched and cattle raids.
The government and the UN — which has warned the violence could lead to a “major tragedy” — were beefing up their forces in Pibor as a column of 6,000 armed youths from the Lou Nuer tribe marched on the town pursuing a rival tribe.
Lise Grande, the UN humanitarian coordinator for South Sudan, told AFP that the number ofgovernment forces heading to Pibor in the troubled Jonglei state was estimated at 3,000 troops and 800 police.
“The government is firmly in charge of the situation and is taking very bold steps. They are deploying large numbers of infantry soldiers and police who are already moving towards Pibor,” she said.
“We remain on high alert and are very concerned that civilians may be at risk,” she said, adding that the United Nations was evacuating the most vulnerable civilians from the town and that the situation remained “very fluid”.
“Our understanding is that there has been damage to the periphery of the town, including the torching of tukuls (thatched huts) and that the compound of one humanitarian organisation has been taken over.
“But it appears that in the main part of town damage is limited.”
By Sunday evening, most of the tribal youths appeared to have entered the town, but have caused only limited damage to property, a humanitarian source in Juba told AFP, asking not to be named.
Parthesarathy Rajendran, head of mission at Doctors without Borders (Medecins sans Frontieres – MSF) said staff at its hospital in Pibor town and two outreach clinics in the area have for the most part fled into the bush.
“What we are hearing is that our clinic has been damaged and a lot of things looted,” he told AFP.
“Since the start of the fighting one week before, the whole population has started displacing and running into the bush,” he said, adding that MSF is the sole provider of health care in Pibor county.
The Lou Nuer youths, several hundred of whom had arrived on the outskirts of Pibor on Friday, were pursuing members of the Murle tribe who began fleeing towards Pibor several days ago after the Lou Nuer raided the town of Lukangol.
The MSF spokesman said Lukangol had been reduced to ashes.
A group calling itself the Nuer Youth White Army issued a statement on December 26 vowing to “wipe out the entire Murle tribe… as the only solution to guarantee long-term security of Nuer cattle”.
The group accuses the Murle of raiding Nuer cattle and killing members of their tribe since 2005, when a peace agreement ended two decades of civil war and led to South Sudan’s independence this year.
Neither the United Nations nor South Sudan’s former rebel army the SPLA have protected the Nuer, the group claimed.
“We the Nuer Youth have decided to fight the Murle, SPLA and the UN,” it said.
To assist those left in the town, the UN’s World Food Programme flew in a helicopter with food on Saturday, Grande said.
The United Nations had raised the alarm in September over cattle raids in the region that had already left around 1,000 people dead since June, describing the situation as a crisis that threatened to engulf the fledgling nation.
The raids involved “army-like” movements of people with new weapons and satellite phones, the United Nations said at the time.
“I am deeply concerned to learn of reports of this imminent large scale attack on civilians in Jonglei state,” Hilde Johnson, who heads the UN Mission in South Sudan (UNMISS), said in a statement on Monday.
“The government must act now if we are to avert a major tragedy.”
The South separated from Khartoum-led Sudan in July after an overwhelming vote for independence following decades of conflict that left some two million people dead.