South Sudan's SSLA Unity State rebels 'cease fire'
The biggest rebel movement in the newly independent South Sudan has declared a ceasefire, its spokesman says.
The South Sudan Liberation Army (SSLA) has been involved in clashes with the new nation's army this year.
Its fighters are concentrated in Unity State, near many of South Sudan's lucrative oil fields.
When South Sudan split from Khartoum last month, its President Salva Kiir offered an amnesty to various militias fighting in the south.
South Sudan's army spokesman told the BBC he had not heard about a ceasefire, but confirmed there had been "behind doors" contacts between the government and the SSLA.
South Sudan's independence from Sudan was the outcome of a 2005 peace deal that ended decades of conflict between north and south in which some 1.5 million people died.
The BBC's James Copnall in Sudan's capital, Khartoum, says insecurity is one of the greatest challenges facing the new state of South Sudan.
The SSLA, led by a dissident general Peter Gadet, is the most significant militarily of the half dozen or so southern rebel groups, our reporter says.
His fighters took up arms earlier this year in protest against corruption, mismanagement of oil revenues and what they believe is the domination of the Dinka ethnic group.
Most of the SSLA are from the Nuer ethnic group, the second biggest in South Sudan.
"We are declaring a ceasefire and we are also accepting the amnesty offered by the president as the basis of talks with the government of South Sudan," SSLA spokesman Bol Gatkouth Kol told the AFP news agency.
The group's intention was to integrate its soldiers into the southern army, he said.
He told the BBC he was in South Sudan's capital, Juba, as the head of an SSLA delegation for further talks.
If the ceasefire is confirmed and then holds, it will be a major step forward for South Sudan's stability, our reporter says.
Last month, the leader of another South Sudanese rebel group - Col Gatluak Gai - was shot dead not long after agreeing to integrate his forces.
One of his daughters is married to Gen Gadet.
The army denied it was behind his assassination and said he was killed in a dispute with a fellow rebel leader about the peace agreement.
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.