Sudan, South Sudan leaders edge closer to border deal: diplomats ADDIS ABABA (Reuters) - Sudan and South Sudan are close to sealing a border security deal that could restart oil production but a signing ceremony envisaged for Wednesday was postponed amid last-minute haggling over details, sources close to the talks said. Sudanese President Omar Hassan al-Bashir and South Sudanese counterpart Salva Kiir have met six times since Sunday to iron out a pact key to reviving their economies after their armies came close to all-out war along a disputed frontier in April. "It is being finalized now," a diplomat familiar with the negotiations told Reuters. The African Union has been striving to broker the agreement and the U.N. Security Council has warned of sanctions against both states if no deal is done. Ethiopia's government, playing host to the talks, arranged for a news conference in the afternoon with officials preparing a ballroom with name plates for both leaders to sign several agreements to wrap up three weeks of negotiations. But when the first diplomats arrived at the hall to verify seating arrangements, Ethiopian and delegation officials said the signing would be postponed, probably until Thursday. By nightfall the northeast African neighbors were still discussing the nitty-gritty of a deal that would provide for a demilitarized buffer zone along the border, according to diplomats and delegation sources. The U.N. set a September 22 deadline for a deal but that was informally extended until the end of the Addis Ababa summit. "There is a political will between... (the two leaders) to reach now an agreement on all conflicts," Sudan's state radio said, quoting foreign ministry spokesman el-Obeid Morawah. He said talks were continuing over some issues but added: "It is clear that both sides have edged closer (to a deal) and achieved great understanding in the past two days." Last month the sides reached an interim deal to restart oil exports from the landlocked South through the north to Red Sea ports after Juba turned off wells in a row over transit fees. While the security deal will provide both nations with oil revenues needed to stave off economic collapse, they have yet to sort out several other conflicts left over from South Sudan's secession in July 2011. They still need to agree on marking their 1,800-km (1,200-mile) long border where there are at least five disputed strips. Their fate will probably have to be decided in future talks or through lengthy international arbitration. Bashir and Kiir have been also discussing a solution to the disputed border region of Abyei but earlier plans for a referendum stumbled on discord over who should be able to vote. The two presidents are also expected to sign deals to boost cross-border trade and grant citizens of both nations residency in the other's country, ending uncertainty for South Sudanese living in Sudan. The summit had originally been scheduled to take place in the South Sudanese capital Juba in April but was cancelled after border fighting broke out and South Sudan briefly seized an oilfield vital to Sudan's economy. Experts say resuming oil flows will take several months as the two export pipelines running through Sudan were filled with water to prevent gelling. Some oil facilities were also damaged during the fighting. South Sudan, where most people follow Christian and animist beliefs, seceded from the mainly Muslim north in July 2011 under a 2005 peace agreement that ended decades of civil war. There was no sign of progress in indirect talks held in Addis Ababa between Sudan and the rebel Sudan People's Liberation Movement-North (SPLM-North), which is fighting the Sudanese army in two areas bordering South Sudan. Diplomats say each country support the other's rebels. Editing by Yara Bayoumy and Mark Heinrich