The rival delegations have held dragging talks that began several months before South Sudan split Africa’s biggest nation in two in July 2011, when it seceded after a landslide independence vote following decades of war.
Among issues on the table Sunday are expected to be ownership of contested regions along their frontier – especially the flashpoint Abyei region – as well as the setting up of a demilitarised border zone after bloody clashes.
The buffer zone would also potentially cut support of rebel forces in Sudan’s crisis-hit Southern Kordofan and Blue Nile regions, where Sudan accuses Juba of supplying former civil war comrades Khartoum now seeks to wipe out.
Multiple rounds of talks have failed to find solutions, but both sides have said they are now optimistic, amid the looming threat of United Nations Security Council sanctions, and the positive sign of the presidents meeting face-to-face.
“We are still facing difficulties… but we are hopeful we can reach a deal,” said Atif Kiir, spokesman of South Sudan’s delegation to the African Union mediated talks in the Ethiopian capital.
“The summit is to reach a comprehensive agreement between the two countries, so let us hope,” his Sudanese counterpart Badr el-din Abdullah told reporters late on Saturday, in a brief break from negotiations that stretched into the night.
A UN deadline passed on Saturday for Sudanese President Omar al-Bashir and his Southern counterpart Salva Kiir to settle the raft of key issues unresolved when the South became the world’s newest nation last year.