Abyei: Sudan troops to withdraw from disputed region
North and South Sudan have agreed to withdraw unauthorised troops from the disputed region of Abyei, the UN says.
There have been several recent clashes in the area, which both sides claim.
South Sudan is preparing to secede from Africa's biggest country in July, after 99% of voters backed independence in January's referendum.
Last month, President Omar al-Bashir threatened not to recognise the new state if it tried to claim Abyei.
Both sides have accused the other of sending unauthorized troops and militia to Abyei, in contravention of the 2005 peace deal which ended decades of conflict between north and south.
These fighters are to be withdrawn and replaced with joint patrols, according to the deal brokered by the UN mission in Sudan.
The withdrawal is due to start on Tuesday and to be completed within a week.
The BBC's James Copnall in Sudan says the agreement is significant, as long as it is respected.
He says previous deals have not been implemented.
Abyei should also have held a vote in January on whether to join north or south, but it was delayed by a dispute over who should cast a ballot.
A draft version of South Sudan's interim constitution explicitly claims Abyei is in the south.
President Bashir, and the Arab Misseriya nomads, are equally adamant the region is in the north.
A southern ethnic group, the Dinka Ngok, are permanent residents of the region, but the Misseriya spend part of every year in Abyei as they seek pastures for their cattle.
Misseriya and Dinka Ngok cattle herders often clash, allegedly with the support of the northern and southern armies.
Our correspondent says the fear is that a localised conflict in Abyei could fracture the fragile north-south peace.
Both Sudan and the South are reliant on their oil revenues, which account for 98% of South Sudan's budget. But the two countries cannot agree how to divide the oil wealth of the former united state. Some 75% of the oil lies in the South but all the pipelines run north. It is feared that disputes over oil could lead the two neighbours to return to war.
Although they were united for many years, the two Sudans were always very different. The great divide is visible even from space, as this Nasa satellite image shows. The northern states are a blanket of desert, broken only by the fertile Nile corridor. South Sudan is covered by green swathes of grassland, swamps and tropical forest.
Sudan's arid north is mainly home to Arabic-speaking Muslims. But in South Sudan there is no dominant culture. The Dinkas and the Nuers are the largest of more than 200 ethnic groups, each with its own languages and traditional beliefs, alongside Christianity and Islam.
The health inequalities in Sudan are illustrated by infant mortality rates. In South Sudan, one in 10 children die before their first birthday. Whereas in the more developed northern states, such as Gezira and White Nile, half of those children would be expected to survive.
The gulf in water resources between north and south is stark. In Khartoum, River Nile, and Gezira states, two-thirds of people have access to piped drinking water and pit latrines. In the south, boreholes and unprotected wells are the main drinking sources. More than 80% of southerners have no toilet facilities whatsoever.
Throughout the two Sudans, access to primary school education is strongly linked to household earnings. In the poorest parts of the south, less than 1% of children finish primary school. Whereas in the wealthier north, up to 50% of children complete primary level education.
Conflict and poverty are the main causes of food insecurity in both countries. In Sudan, many of the residents of war-affected Darfur and the border states of Blue Nile and South Kordofan, depend on food aid. The UN said about 2.8m people in South Sudan would require food aid in 2013. The northern states tend to be wealthier, more urbanised and less reliant on agriculture.