The first observers are preparing to monitor a demilitarized buffer zone between Sudan and South Sudan.

The first observers are preparing to monitor a demilitarized buffer zone between Sudan and South Sudan, Khartoum's defense minister said on Wednesday, a move which aims to curb cross-border rebel support.

Analysts say both countries will face a major challenge to effectively implement the zone along their undemarcated and disputed frontier.

"The mechanism we agreed on has begun working," Defense Minister Abdelrahim Mohammad Hussein told reporters after returning from Addis Ababa.

He also said his country was ready to engage for the first time in talks with the rebels who have been fighting for almost two years in South Kordofan and Blue Nile states.

The monitors, who will include United Nations peacekeepers, are to verify the withdrawal of Sudanese and South Sudanese forces from the buffer zone, 10 kilometers (6.2 miles) on each side of the 1956 border.

At talks in the Ethiopian capital this month, Sudan and South Sudan -- which have engaged in months of intermittent clashes -- finally settled on detailed timetables to ease tensions by implementing the buffer zone and key economic pacts.

At the African Union-led talks in Addis Ababa, Sudan softened its stance on the security guarantees, helping the buffer zone and eight other agreements to go ahead, observers said.