High numbers of civilians have been killed and wounded in attacks by suspected rebels in South Sudan's conflict-wracked and impoverished Jonglei state, the United Nations and officials said Monday.
Authorities in South Sudan said 78 people were killed in Sunday's attacks on villages in Twic East county, and blamed fighters loyal to anti-government rebel leader David Yau Yau.
"The attacks resulted in high numbers of killed and wounded," the United Nations Mission in South Sudan (UNMISS) said in a statement condemning the violence.
"As soon as the fighting had stopped yesterday, the UN Humanitarian Air Service (UNHAS) flew health partners to the attacked areas to evacuate casualties," it said, adding that 31 seriously wounded civilians were airlifted out.
"They also reported more wounded civilians remaining in the area and this morning UNHAS dispatched a helicopter to continue the medical evacuations," the statement said, adding that UN investigators had also been sent to the area to "investigate the attacks, ascertain the identity of the attackers, and determine the accurate number of casualties."
UNMISS said two attacks were made against cattle camps in the Ajong Payam and Pakeer Payam areas, with subsequent attacks in a couple of other locations also reported.
Jonglei was one of the areas hardest hit in Sudan's 1983-2005 north-south civil war, which ended in a peace deal that paved the way for the South's full independence.
Tit-for-tat cattle raids and ethnic killings are common in the severely under-developed state, awash with guns left over from the civil war.
Twic East County's commissioner, Dau Akoi Jurkuc, told AFP the attacks took place in an area already hit by Yau Yau's rebel forces in August this year, and put the toll from Sunday's violence at 78 dead, 87 wounded, 14 missing and 24 abducted -- many of them children.
He said the rebels descended on the villages with heavy weapons, automatic rifles and rocket-propelled grenades, massacring civilians, burning homes, stealing cattle and leaving "fear and panic" in their wake.
There was no army presence in the area when the attacks occurred, Dau said, adding that the eight policemen posted in Pakeer Payam were all killed in the attacks.
"The terrain made it very difficult for the army to intervene. Because the area is flooded, vehicles cannot move, it's hard for the army to move," South Sudan's army spokesman, Colonel Philip Aguer, told AFP.
South Sudan's rebel-turned-official army has been fighting in the region to crush a rebellion led by Yau Yau, who comes from the Murle people, since 2010.
South Sudan has repeatedly accused Khartoum of supporting militias, including Yau Yau, fighting its government, and the violence came ahead of a planned visit to Juba on Tuesday by Sudanese President Omar al-Bashir.
Relations between north and south are already on edge over the fate of the disputed Abyei region, a volatile, oil-producing area left in limbo following the divorce of the two Sudans.
Plans for a referendum on the future of Abyei have been repeatedly stalled, prompting regional leaders loyal to the south to hold their own vote. The United Nations has previously warned that any such unilateral move would risk inflaming tensions in the area and between north and south.