South Sudan holds final rallies ahead of secession vote
Final rallies have taken place in south Sudan's capital, Juba, ahead of Sunday's vote on independence for the south of the country from the north.
The BBC's Peter Martell in Juba says there has been a carnival atmosphere as hundreds of people took part in what is called the "final walk to freedom".
Later this evening, there will be a concert where musicians will celebrate the referendum.
It is part of a 2005 deal that ended a two-decade north-south civil war.
'There will be no war'
US envoy to Sudan Scott Gration has told the BBC he is optimistic the referendum will take place successfully.
He said the north and south had reached out to each other in recent days and promised not to destabilise each other.
"It has been a tough ride until now but the parties have really come through. [They] have made agreements," he told the BBC.
On Wednesday, a ceasefire was signed by the authorities in Southern Sudan with a renegade officer, Lt Gen George Athor.
Gen Gration added that the south had promised Sudanese President Omar al-Bashir that it would not support rebels from Darfur.
He also said he had had reports that the ruling party in the south had asked some Darfur rebels to leave and that they had moved back into the northern region or into other countries.
Analysts say President Bashir is under intense pressure from northern politicians, who fear that the secession of the south may lead to a further splintering of the country.
Meanwhile Uganda's leader Yoweri Museveni has said the referendum would be an opportunity to enhance security and stability in East Africa.
During the civil war he backed the southern rebel movement, while the Sudanese government supported the Ugandan Lord's Resistance Army rebel group.
"If the people of Southern Sudan decided to stay with Khartoum willingly then, of course, there will be no war," he told the BBC's Network Africa.
"On the other hand, if they decide to go away and form their own country then there will be no war.
"So either way that benefit will be there, the benefit of better security."
But the Kenyan mediator who negotiated the Sudanese peace deal says he regrets the forthcoming division.
"I had always thought I do not want to go down in history as the person who mediated the split of the biggest country, the richest country in Africa," Gen Lazarus Sumbeiywo told the BBC.
"But I don't have a vote - it is the Sudanese who are going to decide."
Our reporter in Juba says Friday morning's rally started at the city's football stadium and proceeded to the grave of John Garang, the late southern rebel leader who signed the peace deal with Khartoum.
He says people were dancing on top of trucks, listening to music and singing along to songs in support of separation.
Many school children and students also joined the parade.
"We are Christian, they are Arab, and they are Muslim. Why unite with them?" Paul, a secondary student, told the BBC.
Cheers rang out when the march passed a giant countdown sign, our reporter says.
"I will not be a second-class citizen, I want to be the first only, so that is why I am happy," another marcher, Anne, said.
Southern complaints about discrimination by the northern government were a key factor behind the years of north-south conflict.
At an event on Friday afternoon, former South African President Thabo Mbeki - the African Union's mediator on Sudan - said the vote marks the "true emancipation" of the people of the south.
"The work of freedom is just at its beginning. We are confident that the southern Sudanese people have the strength and spirit to succeed in that endeavour," he told a large crowd.
The organisers of the concert are promising Juba residents a top billing of four popular musicians.
Southern Sudanese will have a week to cast their vote on the future of the region, one of the least developed areas in the world.
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.