Fears grew Sunday of heavy casualties in South Sudan's Jonglei state following more than a week of bitter tribal fighting, after the UN reported at least 200 wounded were found in just one village alone.
"Some 200 casualties have arrived in Manyabol", a remote village in the troubled eastern state of Jonglei, where militia gunmen from rival ethnic groups have been battling, said Toby Lanzer, the top United Nations humanitarian official in the country said.
Manyabol is only one settlement in a vast region affected by the fighting, fuelling concerns that the number injured or killed elsewhere in the impoverished state could be far higher.
No figures were given on any possible deaths, but Lanzer called on leaders "urgently to halt the cycle of violence that is leading to senseless loss of life and suffering amongst civilians."
Previous such attacks in the conflict-wracked region have seen hundreds, and possibly thousands, of civilians killed.
The UN were airlifting the most critically injured to Jonglei's state capital Bor for medical treatment, where Doctors Without Borders (MSF - Medecins Sans Frontieres) are supporting the basic hospital.
"We've seen gunshot wounds and leg fractures," MSF spokesman Martin Searle told AFP, adding that they had received 22 patients so far. "We're expecting more."
Tit-for-tat cattle raids and reprisal killings are common in this grossly under-developed state, awash with guns left over from almost two decades of civil war.
But the latest upsurge in fighting that began more than a week ago is of a different scale and nature.
Local government officials have reported columns of hundreds -- if not thousands -- of gunmen in a tribal militia fighting their way towards the heartland of a rival community.
Lou Nuer gunmen from northern Jonglei are heading south towards Pibor, an area of their rivals, the Murle.
South Sudan's rebel-turned-official army has also been fighting in the region to crush a rebellion led by David Yau Yau, who comes from the Murle people, since 2010.
Lanzer added that "thousands of civilians" are feared to be hiding in the bush without shelter following the clashes.
An AFP reporter who flew low over Manyabol and other parts of Jonglei on Friday reported sighting huts on fire and the charred remains of others that had been razed to the ground.
Lines of men in green battledress were also spotted, marching southwards carrying guns.
US State Department officials said this week they were "deeply disturbed by mounting reports of abuse of civilians, including targeted killings, rape (and) beatings."
European ambassadors in Juba warned Saturday that the clashes would "exacerbate an already critical humanitarian situation".
Rights groups accuse all sides of abusing and raping civilians.
The clashes echo attacks in December 2011, when some 8,000 Lou Nuer marched south killing and looting in what they said were reprisals for earlier attacks and cattle raids by Murle fighters.
The UN later estimated over 600 people were massacred, although local officials reported the figure to have been far higher.
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.