Sudan and South Sudan have begun talks to deploy a joint force to protect oilfields in the South threatened by rebels, Sudan’s foreign minister says.
The news comes after Sudan’s President Omar al-Bashir flew to South Sudan to discuss the unrest there with his counterpart, Salva Kiir.
The conflict pits supporters of Mr Kiir against rebels led by his sacked deputy, Riek Machar.
At least 1,000 people have been killed since violence erupted on 15 December.
The violence started after Mr Kiir accused Mr Machar of attempting a coup – an allegation he denies.
Nearly 200,000 people have been displaced in the conflict, which has taken on ethnic undertones. Mr Kiir is from the majority Dinka community and Mr Machar from the Nuer group.
On Monday, Sudan’s Foreign Minister Ali Karti said Mr Bashir and Mr Kiir were “in consultations about the deployment of a mixed force to protect the oilfields in the South”.
However neither of the presidents referred to the proposal during their joint news conference in the South Sudanese capital Juba.
When it seceded from Sudan in 2011, South Sudan ended up with most of the oilfields.
South Sudanese President Salva Kiir (L) welcomes his Sudanese counterpart Omar al-BashirNearly 200,000 people have been forced from their homes in the conflict
But it has to export the oil using pipelines through ports in Sudan’s territory. The government in Khartoum now fears its oil revenue will be disrupted by the fighting in the South.
The BBC’s South Sudan analyst James Copnall says it will be an extraordinary development if Sudanese forces return to the South.
At least two million people died during the north-south conflict.
Separately, the two warring parties in South Sudan have begun direct talks in Ethiopia aiming at a ceasefire.
Analysts say that by seizing Bentiu, the capital of the oil-producing Unity State, the rebels have in effect been able to hold the country to ransom and made their bargaining position much stronger.
However, not much progress has been made at the Ethiopia talks so far, Mr Kiir said at the news conference with President Bashir.
He said his government would not meet Mr Machar’s demand to release 11 of his political allies accused of plotting a coup.
They would be held accountable for the violence in South Sudan, Mr Kiir added.
The BBC’s Alastair Leithead was with government troops when they were ambushed
President Bashir called on the two sides to end the conflict through dialogue, saying Sudan would not back the rebels.
China’s Foreign Minister Wang Yi is also due to hold talks with the opposing factions, in an attempt to push them to agree to a cessation of hostilities.
China is a major investor in South Sudan’s oil industry.
Also on Monday, the United Nations said militiamen had taken control of a UN food warehouse in Bentiu and that UN vehicles had been commandeered in the rebel-held town of Bor.
“This makes it very, very difficult for us to continue our work – the sole purpose of which is reaching civilians in need,” said Toby Lanzer, the UN’s humanitarian co-ordinator in South Sudan.
Heavy fighting is continuing to the south of Bor, says the BBC’s Alastair Leithead, who was on the road between Juba and Bor.
The rebels include a former military division made up of thousands of men who switched sides, our correspondent says.
Until a ceasefire is agreed, fighting is expected to continue or even intensify, he adds.
The latest trouble has its roots in tensions that go back long before 2011.
Fighting erupted in the South Sudan capital, Juba, in mid-December. It followed a political power struggle between President Salva Kiir and his ex-deputy Riek Machar. The squabble has taken on an ethnic dimension as politicians’ political bases are often ethnic.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.Both Sudan and the South are reliant on oil revenue, which accounts for 98% of South Sudan’s budget. They have fiercely disagreed over how to divide the oil wealth of the former united state – at one time production was shutdown for more than a year. Some 75% of the oil lies in the South but all the pipelines run northThe two Sudans are very different geographically. 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.After gaining independence in 2011, South Sudan is the world’s newest country – and one of its poorest. Figures from 2010 show some 69% of households now have access to clean water – up from 48% in 2006. However, just 2% of households have water on the premises.Just 29% of children attend primary school in South Sudan – however this is also an improvement on the 16% recorded in 2006. About 32% of primary-age boys attend, while just 25% of girls do. Overall, 64% of children who begin primary school reach the last grade.Almost 28% of children under the age of five in South Sudan are moderately or severely underweight – this compares with the 33% recorded in 2006. Unity state has the highest proportion of children suffering malnourishment (46%), while Central Equatoria has the lowest (17%).