Sudan border clashes: African Union, UN, call for peace
The African Union (AU) is calling on Sudan and South Sudan to abide by a plan that will see both parties pull forces out of a disputed border area.
A senior AU official called for hostilities to cease in areas bordering lucrative oil fields.
The United Nations Security Council has also called for an end to aerial bombardments by Sudanese forces.
South Sudan's President Salva Kiir has said that Sudan has "declared war" on his country.
Recent clashes between Sudan and newly independent South Sudan over the Heglig oil field and nearby towns have raised fears of a return to war.
Meanwhile, South Sudan's government says 17 prisoners of war from Sudan will be released on Wednesday in response to diplomatic efforts by Egypt.'Outside help'
Outlining details of a proposed peace deal, AU official Ramtane Lamamra said the African Union would take "appropriate measures" if either country failed to implement the proposed plan.
He said the AU wanted both parties "formally conveying their commitment" to peace within 48 hours.
And he said both Sudanese and South Sudanese forces should pull out of the disputed area of Abyei, near Heglig, within two weeks.
Main disputes between the two Sudans
- Transit fees the South should pay Sudan to use its oil pipelines
- Demarcating the border
- Both sides claim Abyei
- The rights of each other's citizens now in a foreign country - there are estimated to be 500,000 southerners in Sudan and 80,000 Sudanese in the South
- Each accuses the other of supporting rebel groups on its territory
South Sudan's information minister said the African Union needed external assistance to solve the crisis.
"The African Union has not done what it is supposed to do, they are talking now of a road map," Barnaba Benjamin told the BBC's Network Africa programme.
"We have been prepared for this road map, we were ready to sign the citizenship agreement, we were ready to sign the agreement on the demarcation of borders, but the Sudanese government walked away on the day of the signing and the next day they attacked us in our position.
"So that's why we think that countries like Egypt and its influence within the Arab League, its influence at the African Union can also play a positive role."
South Sudanese President Salva Kiir is cutting short his visit to China due to "domestic issues", AFP news agency quoted a Chinese official as saying.
China, a major buyer of oil from both Sudan and South Sudan, has urged both parties to show restraint in the conflict.
The UN Security Council also demanded the cessation of violence and said it will consider what steps to take in order to prevent all-out war.
The Security Council last week discussed the possibility of imposing sanctions on the two countries if the violence did not stop.
Susan Rice, the US ambassador to the United Nations said: "We strongly condemn Sudan's incursion into South Sudan and, in particular, its heavy aerial bombardments of civilian areas and infrastructure, and we call for the immediate cessation of hostilities.
"We recognise the right of South Sudan to defend itself and urge South Sudan to exercise maximal restraint in its reaction to Sudan's attacks."
In January, South Sudan shut down oil production, which provides 98% of its revenue, after Khartoum impounded South Sudanese oil shipments amid a dispute over transit fees.
South Sudan took most of the former united Sudan's oil reserves when it seceded in July 2011 but relies on pipelines to seaports in Sudan to export it.
Independence came as part of a peace deal to end two decades of conflict in which some 1.5 million were killed.
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.