ADDIS ABABA - South Sudan's warring parties opened negotiations Friday to end nearly three weeks of raging conflict in which thousands are feared dead and that has taken the world's youngest nation to the brink of all-out civil war.
Government and rebel negotiating teams are at a luxury hotel in neighbouring Ethiopia's capital Addis Ababa, with the rivals first meeting special envoys from regional nations.
But fighting is continuing in the world's newest nation, with the army vowing to retake the town of Bor from rebel forces for a second time.
Ongoing battles prompted the top UN aid official in South Sudan Toby Lanzer to warn Friday that soldiers and rebels must protect civilians and aid workers, or risk worsening a situation he described as "critical".
Ethiopia's foreign ministry confirmed that negotiations had started, adding that the regional East African bloc IGAD that is helping broker a deal "was committed to support in any way possible".
Sources suggested the rivals may not meet directly until at least Saturday.
"We are participating in talks because we want peace for our people even though the rebel groups have not accepted a cessation of hostilities," the government said in a statement late Thursday.
Thousands of people are feared to have been killed in the fighting, pitting army units loyal to President Salva Kiir against a loose alliance of ethnic militia forces and mutinous army commanders nominally headed by ex-vice president Riek Machar.
Fighting erupted on December 15 when Kiir accused Machar of attempting a coup in the oil-rich but impoverished nation.
Machar has denied this, in turn accusing the president of conducting a violent purge of his opponents and refusing to hold direct talks with Kiir.
Civilians in dire need of aid
Fighting has spread across the country, with the rebels seizing several areas in the oil-rich north.
Aid workers have increased warnings of a worsening crisis for civilians affected by the conflict.
"All parties to the conflict have a responsibility to make sure that civilians are spared from the fighting," said Lanzer, the UN humanitarian coordinator.
"We call on all parties to facilitate aid agencies' access to civilians, and to protect and respect humanitarian activities."
Almost three weeks of violence has forced around 200,000 people to flee their homes and "affected many hundreds of thousands of people indirectly", Lanzer added.
Some 57,000 are seeking refuge with badly overstretched UN peacekeepers.
The UN peacekeeping force said this week "atrocities are continuing to occur" across the country, which won independence from Sudan in 2011 after decades of civil war.
One of the hardest hit areas is the rebel-held town of Bor, the capital of Jonglei state and situated just 200 kilometres (125 miles) north of the capital Juba, which has changed hands three times since the fighting erupted.
On Thursday, army spokesman Philip Aguer said troops were "advancing again" on the town.
Tens of thousands have fled, many paddling in simple boats across the White Nile river to escape the fighting to Awerial in neighbouring Lakes.
Amid the fighting, the talks in Addis Ababa have been welcomed.
UN special envoy Hilde Johnson stressed the need for "reconciliation and healing".
The conflict has been marked by an upsurge of ethnic violence pitting members of Kiir's Dinka tribe against Machar's Nuer community.
The United Nations reported "extra-judicial killings of civilians and captured soldiers" and the "discovery of large numbers of bodies" in the capital Juba as well as in the towns of Bor and Malakal.
The army has set up committees into the killing of "innocent people", the government said Thursday, and another into the bitter infighting within the presidential guard units that were the reported first shots in the conflict.
On Tuesday, Machar told AFP that he was not yet ready to agree to an immediate ceasefire nor hold face-to-face talks with Kiir.
Kiir has described the war as "senseless", but has ruled out power sharing with the rebels.
"If you want power, you don't rebel so that you are awarded with the power," Kiir said in an interview broadcast on the BBC.