The talks are aimed at reaching a ceasefire deal and end weeks of ethnic fighting in the world’s youngest state.
At a ceremonial opening to the talks at a luxury hotel in the Ethiopian capital Addis Ababa on Saturday, the leaders of the rival delegations hugged, but the faltering start to the negotiations has dampened hopes for a swift end to the violence.
The run-up has been overshadowed by continued clashes between President Salva Kiir’s SPLA government forces and rebels loyal to former vice president Riek Machar centred on the strategically located town of Bor.
The talks will focus on when and how to roll out the ceasefire that both sides have agreed to in principle, though neither has indicated a start date.
The head of the rebel delegation in Addis Ababa, Taban Deng Gai, repeated Machar’s call for the release of several senior politicians allied to Machar and for the state of emergency imposed by Kiir in two states of South Sudan to be lifted.
“We ask for … the release of political detainees and … free movement and political space for them to join us here,” Gai said at the opening ceremony.
Dina Mufti, spokesman for Ethiopia’s foreign ministry, told reporters that the direct talks would begin at 1200 GMT on Sunday.
Western and regional powers, many of which supported the negotiations that led to South Sudan’s independence from Sudan in 2011, are pressing for a peace deal, fearing the new fighting could slide into civil war and destabilize east Africa.
Clashes have already killed more than 1,000 people, driven 200,000 from their homes and rattled oil markets.