Sudan's defense minister says a referendum on independence for the country's south may have to be delayed.
This is the first time a senior member of Sudan's ruling National Congress Party has publicly suggested postponement of the referendum, now scheduled for January 9.
Abdel Rahim Hussein told reporters in Cairo Tuesday that issues such as the north-south border and control of the oil-rich Abyei region must be resolved, "within the framework of one nation."
He said "logic and reality" suggest the vote should be postponed.
Northern officials had previously called for delay of a separate vote on whether the Abyei region becomes part of the north or the south.
Tension in Sudan has been rising as the polls draw near. Both sides have accused the other of building up troops in north-south border areas.
The two votes are key parts of the 2005 peace agreement that ended Sudan's north-south civil war. Observers say preparations for both votes are running well behind schedule.
The NCP and the government of President Omar al-Bashir have been campaigning to keep Sudan unified. However, most analysts say that southern voters will choose independence.
On Monday, the head of the U.N. mission in Sudan said peacekeeping troops are being concentrated along sensitive parts of the north-south border, with the goal of maintaining peace and stability.
Southern President Salva Kiir asked the U.N. Security Council earlier this month to place more troops on the border to create a buffer zone. U.N. mission chief Halie Menkerios said the U.N. has not made a decision on sending more troops.
Some information for this report was provided by AP and Reuters.