South Sudan's government is to resume peace talks with rebels in the Ethiopian capital Addis Ababa, as a ceasefire signed by the two sides in January continues to unravel.
The talks, set to begin on Monday, come amid optimism that the two sides could make progress after the government freed four officials it had been holding since last December, having accused them of masterminding a failed coup.
The officials freed included the former secretary general of the governing party, the Sudan People's Liberation Movement.
Despite the optimism, Al Jazeera's Anna Cavel from Juba, South Sudan's capital, said some people were "jaded with the [peace] process" because of a lack of progress.
The talks will coincide with a visit to South Sudan by the UN's top human rights official Navi Pillay.
Joe Contreras, a spokesman for the UN Mission in South Sudan, said Pillay arrived in Juba on Monday on a joint mission with Adama Dieng, the UN's special envoy for the prevention of genocide.
The two are expected to remain in the country for two days and investigate the situation on behalf of UN chief Ban Ki-moon. They are expected to meet President Salva Kiir and other senior officials.
Last week, the UN Security Council brandished the threat of sanctions against South Sudan government forces, loyal to Kiir, and rebels who support former vice president Riek Machar.
Both sides have been implicated in atrocities and war crimes including massacres, rape, attacks on UN bases sheltering civilians from ethnic violence and the recruitment of child soldiers.
Last week, the rebels were blamed for the killing of hundreds of people in the oil hub of Bentiu, while a pro-government mob killed dozens of civilians in an attack on a UN base in Bor.
Kiir's government has been fighting Machar's forces - a mix of army defectors and ethnic militia - since December 15.
The four-month-old war has left thousands, and possibly tens of thousands of people dead, and forced over one million to flee their homes, sparking a major humanitarian crisis.
More than 78,000 civilians are currently crammed into eight UN bases in the country, while more than a million people have been displaced within the country or have fled to neighbouring states, mainly Uganda and Ethiopia.
Violence has also taken on an ethnic dimension, pitting Kiir's Dinka tribe against militia forces from Machar's Nuer people.