Omar al-Bashir, the Sudanese president, is scheduled to hold a summit with his counterpart from South Sudan, Salva Kiir, in Ethiopian capital to wrap up two weeks of negotiations meant to end hostilities between the neighbours, state media has said.
Diplomats earlier said the former civil war foes were coming close to a border security deal that would allow the resumption of oil exports vital to the economies of both countries.
South Sudan seceded from Sudan last year under a 2005 peace deal that ended decades of civil war, but the two have yet to resolve a litany of issues related to partition.
Border clashes almost boiled over into full-scale war in April, although tensions have abated since then.
Bashir had agreed to accept an invitation from Ethiopia to hold a summit with Kiir in Addis Ababa on September 23, SUNA said.
The summit news came after a Western official said both nations had made much progress towards a broader framework agreement to end hostilities by September 22 as demanded by the UN Security Council.
"We appreciate the strong efforts the parties have made towards the outstanding issues and we are confident that they will reach an agreement before the end of the deadline," said Endre Stiansen, a Norwegian special envoy who is mediating the talks. "And the summit is necessary to close this deal."
Norway is a mediator in the talks because it advises both nations on oil issues and is respected as a neutral party.
Sudan objects to border buffer
Landlocked South Sudan shut down its oil output - which accounted for about 98 per cent of its state revenues - in January in a row with Khartoum over how much it should pay to export oil through the north to Red Sea ports.
But the two are "very close" to a final oil transport accord, another diplomat said, adding that the sides were discussing technical aspects of restarting production.
"Discussions for a final oil deal are in the last stage. There is no big obstacle left," a diplomat said.
Diplomats say the main goal now is to get Sudan to agree to a demilitarised border buffer zone, a first step toward settling broader disputes over the volatile, poorly demarcated frontier.
Sudan objects to a map proposed by the African Union which puts a 14km strip inside the South's territory. The land is fertile grazing ground for Arab tribes allied to Khartoum.
But one of the most daunting - the fate of the contested Abyei border region - will not be solved in this round of talks.
Diplomats said the two sides were discussing a deal that would see South Sudan's army pull out of the area, with its ultimate fate to be decided later.
"There is huge pressure on Sudan to say yes to the map. Experts are now discussing how to work around Sudan's security concerns," said a diplomatic source close to the South's delegation. "If Khartoum says no, they will be blamed for the failure so they will probably move towards a compromise."
Once a buffer zone has been agreed, southern oil exports can resume, which would give a lift to both economies and an incentive to both sides to keep discussing other, more complex issues.
Western powers hope for more significant progress once the sides agree to resume oil exports, which would take several months because the pipelines were flooded with water and some oil fields damaged during fighting in April.