Sudan's president and his southern counterpart are meeting to try to end recent fighting along their common border, less than a month before the south's independence.Some 140,000 people have fled the clashes, aid workers say.
The African Union is hosting the peace talks between President Omar al-Bashir and the south's Salva Kiir.
The south's secession follows decades of conflict with the north which left some 1.5 million people dead.
The fighting along the border has raised fears that the conflict could resume.
Former South African President Thabo Mbeki and Ethiopia's Prime Minister Meles Zenawi are mediating the talks in the Ethiopian capital, Addis Ababa.
An AU statement said the talks would focus on the withdrawal of armed forces from the disputed town of Abyei, which northern forces seized last month.
It said the talks would discuss "the dispatch of an African-led international mission to provide security, to provide conditions for the speedy return of displaced people and steps towards a final settlement of the status of the area".
'Southerners targeted' Reuters news agency quotes unnamed diplomats as saying that President Bashir had agreed to withdraw his forces from the town but this has not been confirmed.
US Secretary of State Hillary Clinton, who is to arrive in Ethiopian capital on Monday in the latest leg of her Africa tour, is to meet Mr Kiir but not Mr Bashir, one of her aides told the AFP news agency.
Human rights groups have warned that southerners are being targeted by pro-northern forces in the neighbouring South Kordofan state, which is in the north but is home to many pro-south communities and where there have also been recent clashes.
A northern official has warned the south against supporting "rebels" in South Kordofan, according to the state-run Sudan News Agency, Suna.
Haj Majid Suwar said unless this stopped, it could jeopardise the north's recognition of the south's independence on 9 July.
But a southern military spokesman denied there were any links between the southern army and the pro-south groups fighting in South Kordofan, even though they used to be part of the same rebel group which fought the north for many years.
On Friday, the south accused the northern military of bombing areas in Unity State in order to seize oil fields from the south.
The north-south war ended with a 2005 peace deal, under which the mainly Christian and animist south held a referendum in January on whether to secede from the largely Arabic-speaking, Muslim north.
Some 99% of voters opted for independence. President Bashir said he would accept the verdict of the south, where most of Sudan's oil fields lie.