The presidents of Sudan and South Sudan met for a second day Monday as pressure mounts to settle festering disputes that have brought the rivals to the brink of renewed conflict.Former civil war foes President Omar al-Bashir of Sudan and his Southern counterpart Salva Kiir are facing the looming threat of UN Security Council sanctions unless they reach a deal, after they missed a Saturday deadline.The protracted talks under African Union mediation began in the Ethiopian capital several months before South Sudan split in July 2011 from what was Africa's biggest nation, following a secession vote after decades of war.The leaders met Monday for talks hosted by new Ethiopian Prime Minister Hailemariam Desalegn in the presidential palace, alongside AU chief mediator and former South African president Thabo Mbeki."The presidents met, now they are discussing issues," including contested border areas and oil, said top South Sudanese official Deng Alor.The pair kickstarted the talks with a two-hour meeting late Sunday, following marathon efforts by their rival delegations to close gaps on a raft of issues left unresolved when the South became independent last year.Little information has filtered out about progress of the meeting, but both leaders have been seen smiling and chatting in each other's company.  "There is still optimism some form of a deal can be settled," said a Western diplomat. "There are only a few sticking points left." Key issues include the ownership of contested regions along their frontier -- especially the flashpoint Abyei region -- and the setting up of a demilitarised border zone after bloody clashes. AFP