UN humanitarian chief Valerie Amos Thursday visited conflict-ridden regions of South Sudan, voicing concern over the violence that threatens to destabilise the world's youngest nation.
"Conflict, poverty, and increasing food insecurity are having a major humanitarian impact," said Amos ahead of her trip to remote Jonglei state, where weeks of bloody ethnic violence have affected 120,000 people.
Amos, who is on a three-day visit to the oil-rich but grossly impoverished nation, said she was "concerned about the scope and magnitude of the violence communities have inflicted on each other in Jonglei."
In addition, there were concerns about "conflict between rebel militias and the army that has killed, wounded and displaced so many," the UN under-secretary general for humanitarian affairs and emergency relief coordinator said.
South Sudan -- which declared independence from its former civil war enemy to the north in July -- is already reeling from multiple crises, including ethnic clashes, rebel attacks and some 3 million people needing food aid.
Last month, a militia army of up to 8,000 armed youths attacked a rival ethnic group in Jonglei, with aid workers reporting horrific massacres, including babies beaten against trees and women hacked by machetes.
In addition, refugees are flooding into the South from Sudan's civil war border regions of Southern Kordofan and Blue Nile, where Khartoum is battling rebel forces formerly allied to the now independent South Sudanese army.
Over 80,000 refugees fleeing the fighting have poured into the South since June and the World Food Programme has warned it is preparing for up to 500,000 more refugees if Khartoum continues blocking emergency aid into the warzone.
"South Sudan faces significant challenges, including hundreds of thousands of people displaced in 2011, people returning from Sudan and refugees from the ongoing conflict in Southern Kordofan and Blue Nile states in Sudan," Amos said.
South Sudan is also embroiled in a a furious row over oil pipeline fees with former foe Khartoum, which UN chief Ban Ki-moon said Sunday has become a "major threat" to regional peace and security.
Key issues unresolved at independence have escalated into bitter arguments, including a row over pipeline transit fees to transport the landlocked South's oil to port in the rump state of Sudan.
Juba has said it has completed a shutdown of its oil production -- the fledgling nation's top revenue source -- after it accused Khartoum of stealing ê815 million of its oil and AU-mediated talks stalled.