The
African Union says North and South Sudan have agreed on a framework to
resolve most outstanding issues ahead of a vote on southern
independence.
In a statement, the AU says both sides have agreed to
demarcate the north-south border while allowing northern nomads to graze
in the south. The framework also includes commitments to allow Sudanese citizens the right to live in either North or South Sudan.
Meanwhile, voter registration for January's referendum is due to begin.
The referendum is part of a peace deal which ended a north-south civil war.
The BBC's James Copnall in Khartoum says the announcement from the AU's High Level Implementation Panel on Sudan will reduce some of the tension that has been growing in the build-up to the vote.
The statement said both parties "committed themselves to the immediate demarcation of the north-south border".
"In the event of secession, this will be the longest inter-state border in Africa, hosting in its immediate vicinity on both sides a significant proportion of Sudan's population," the statement said.

Logistical challenge In another development, the much-delayed voter registration for the referendum is begins on Monday.
Registration is starting late, in part because of a number of political disagreements between north and south.
An estimated five million people are eligible to vote, and officials now have a shortened period of 17 days in which to register them.
Denis Kadima, director of the UN's Integrated Referendum and Electoral Division, said most of the materials should be in place, despite the huge logistical challenges, particularly in the South.
South Sudan, which has most of Sudan's oil reserves, is considered likely to vote for independence, but many southerners fear Khartoum will never let their region break away.