ADDIS ABABA  - Sudan and South Sudan’s leaders negotiated positions Sunday as international pressure mounts to end long-running disputes that have brought the former civil war foes to the brink of renewed conflict. The rival delegations have held drawn-out talks that began several months before South Sudan split in July 2011 from what was Africa’s biggest nation, following a landslide independence vote after decades of war. Among issues on the table are understood to be ownership of contested regions along their frontier - especially the flashpoint Abyei region - and the setting up of a demilitarised border zone after bloody clashes. The buffer zone would also potentially cut support for rebel forces in Sudan’s Southern Kordofan and Blue Nile regions, where Sudan accuses Juba of supplying former civil war comrades whom Khartoum now seeks to wipe out. Multiple rounds of talks have failed to find solutions, but both sides have said they are now optimistic, given the looming threat of UN Security Council sanctions and the fact the two presidents were due to meet. “We are still facing difficulties ... but we are hopeful we can reach a deal ,” said Atif Kiir, spokesman for 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 Saturday, when negotiations stretched into the night. A UN deadline passed Saturday for Sudanese President Omar al-Bashir and his Southern counterpart Salva Kiir to settle the raft of issues unresolved when the South became the world’s newest nation last year.