The defence ministers of Sudan and South Sudan are set to meet in the Ethiopian capital on Monday to discuss border security, a South Sudanese official said.

"The extraordinary meeting... will discuss the establishment of the various mechanism, including the joint border verification and monitoring mechanism and the establishment of the safe border demilitarized zone," Juba's chief negotiator Pagan Amum told AFP on Saturday.

Delegations from both countries are in the Ethiopian capital for the first face-to-face talks since deadly fighting along the disputed border in recent weeks brought the foes back to the brink of war.

The United Nations and the African Union (AU) have given the two sides until August 2 to resolve a number of issues, including border demarcation, oil exporting and citizenship issues.

At the close of the fifth day of the AU-led talks, Amum said both sides had agreed to implement the AU and UN-promoted peace plan.

"We are happy that the parties and the panel have agreed to a plan of action to fully implement the (UN) Security Council resolution 2046 as well as the African Union roadmap," Amum said.

But he accused the North of requesting "preconditions" before the broader talks could proceed and said Khartoum was insisting on discussion of security issues ahead of other matters.

"The government of Sudan is attempting to impose a precondition that a certain agenda of security to be discussed first... (that) would be a precondition and that is a violation of the roadmap as well as the Security Council resolution," he said.

Amum added that the AU mediation panel called a meeting for June 7 to discuss Abyei, a disputed territory along the border.

He said the two sides would meet "to discuss the establishment of the administration as well as the establishment of various other structures necessary," for the return to peace.

The current round of talks opened in the Ethiopian capital this week with the South accusing the North of refusing to withdraw its armed forces from Abyei.

The UN called on both sides to remove their troops from the area before May 16. South Sudan complied, but Sudan delayed the withdrawal of their troops until June 1.

Sudan and South Sudan fought a bloody civil war, Africa's longest, before splitting in July. Juba broke away from its northern neighbour, taking with it two thirds of the combined oil revenue.

A number of contested issues, including border demarcation and oil resources, remain unresolved.