The leaders of Sudan and South Sudan have agreed to set up a long-delayed demilitarized zone along their disputed border as soon as possible, a condition for the resumption of oil exports, an African Union mediator said on Saturday.

Sudan's Omar Hassan al-Bashir and South Sudan's Salva Kiir held two days of talks in Ethiopia to try to defuse tensions that brought them close to war in April.

The leaders agreed in September to end hostilities and withdraw their armies from their disputed border, but the two sides have failed to implement the agreement.

"They've ... agreed that actions should be taken as soon as possible to implement all the existing agreements unconditionally," AU mediator Thabo Mbeki said after the summit, which Bashir and Kiir left without giving any statements. Mbeki gave no specific timeframe for the commitment.