ADDIS ABABA - Significant progress has been made at a summit between Sudan President Omar Hassan al-Bashir and his South Sudanese counterpart Salva Kiir, said a spokesman of the Sudanese Foreign Ministry.

Al-Obeid Murawah told reporters late Monday that the summit between the two leaders was going on with significant progress, and it would continue on Tuesday.

"Significant progress has been happening regarding the issue of 40 miles; they also discussed the issue of Abyei, and tomorrow they will continue discussing the issues," he said.

The two leaders have been meeting in Addis Ababa, Ethiopia, since Sunday to discuss and conclude negotiations on outstanding issues, including oil sharing, border demarcation especially the status of the oil-rich area of Abyei, and the establishment of a demilitarized border zone.

"We are expecting to sign maybe a sort of agreement regarding maybe all the issues, or the issue of general agreement," said the spokesman.

Border clashes erupted in April when South Sudan troops and tanks briefly seized the oil-rich border area of Heglig, and Sudan counterattacked with bombing raids.