South Sudan rebel Gatluak Gai killed after peace deal
A key South Sudanese rebel leader, Col Gatluak Gai, who this week signed a peace deal with the government, has been killed.
The exact circumstances of his death are disputed.
Col Gai was shot in the early hours of Saturday morning despite having apparently been reconciled with the South Sudanese army.
South Sudan became independent earlier this month, but is facing at least half a dozen armed rebellions.
The incident happened at or near the district of Pakur in Unity State.
Colonel Gai began his rebellion following elections last year, after the candidate he supported for state governor was controversially declared to be the loser.
This week Col Gai signed a peace agreement with the South Sudan army and was due to be reintegrated into it.
A fellow rebel told the BBC he had been lured into a trap by the army, which then assassinated him.
The army spokesman denied this.
He said Col Gai had been killed in a fight with his deputy, after he had changed his mind about the peace agreement.Ethnic divide
But it is clear this incident will make the remaining rebel leaders less likely to accept the amnesty offered by President Salva Kiir.
According to a rebel leader who knew him, Gatluak Gai was in his 50s, with an imposing, physical presence.
Although he was not an educated man, he was able to recruit soldiers from the sub-sect of his Nuer ethnic group, which has often been in conflict with South Sudan's biggest group, the Dinka.
Col Gai is survived by many children, and nine of his boys fought in his militia.
One of his daughters is married to Gen Peter Gadet, who leads the most active rebel group in South Sudan.
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. The residents of war-affected Darfur and South Sudan are still greatly dependent on food aid. Far more than in northern states, which tend to be wealthier, more urbanised and less reliant on agriculture.