Southerners are now just over six months away from the scheduled start of a vote on whether their region should split away as an independent state, a plebiscite promised under a 2005 accord that ended more than two decades of civil war with the north.
Northern and southern leaders have wrangled for months over the members of the commission which will organise the potentially explosive vote.
Analysts say southerners overwhelmingly want independence and there is a risk of a return to conflict if the north tries to delay or obstruct the vote to keep control of the south’s oil.
Members of Sudan’s parliament voted to approve the nomination of Mohamed Ibrahim Khalil, a veteran law professor as well as a former parliamentary speaker and foreign minister, to chair the new commission.
The body will have to settle the thorny issue of who will be able to vote in the referendum — the vote is reserved for southerners but there are question marks over southerners living outside the south and members of nomadic tribes who regularly cross the north-south border.
It will also have to register voters across the vast, undeveloped territory ahead of the referendum.
Northern and southern leaders are due to start separate negotiations in Khartoum next week on how they would share out oil wealth and debts after the secession referendum, together with other issues including the nationality of southerners in the north and vice-versa.
EU observers, who monitored Sudan’s April national elections on Monday called on Sudan to improve the way it registered voters and collected results in the run up to future votes, including the independence referendum.
"All parties, the north and the south, have an interest in having a very good and controlled referendum … I think peace is a common interest for both parties," said Veronique De Keyser, the head of the EU mission.
The EU mission released its final report on the April elections on Monday, giving more detail of earlier reports that the ballot was marred by voter intimidation and confusion over counting the results, among other issues, but was still a step forward for the country.