Hundreds of thousands of people from across Southern Sudan today began to cast their ballots at the start of the week-long independence referendum.

The poll is certain to result in Africa's largest country splitting in two, with the non-Muslim south seceding from the Arab-led north.

?Everyone was skeptical that the process would go peacefully and smoothly but all indications are that the vote at least this week will go smoothly?, said E.J Hogendoorn, the Horn of Africa Project Director at the International Crisis Group.

?Certainly all indications are that the vote will be for secession,? he said, ?but after that comes the much more difficult task of actually making that dissolution peaceful and stable?.

That task, he added, will have to be addressed under the rubric of the post ?referendum arrangement by the elite in both Khartoum and Juba in the next six months.

Hogendoorn noted that most people within the ruling party, National Congress Party (NCP), are resigned to the fact that the vote will be for secession and they have come to terms with that.

He cautioned, however, that there are a number of issues that have not been resolved that will be very difficult to negotiate.

Among the crucial issues he cited is border demarcation, citizenship of northerners living in the south and southerners living in the north, trade rights and the division of oil revenues when the south becomes an independent state.

Hogendoorn also said there is a fear in Khartoum that the secession of the south may lead to other parts of Sudan following suit. ?The fear is that Northern Sudan will be completely dominated by the NCP if in fact the political dispensation remains what it is right now?.

And what that really means, he explained, ?is that there will be very little political space for opposition parties or for the so called marginalized regions of northern Sudan to have a say in Khartoum and to speak about how resources can be more fairly allocated in what remains of Sudan.?

Hogendoorn acknowledged the concern among many in the African Union (AU) about the Sudan referendum undermining the legitimacy of African colonial borders and setting a precedent for African secessionist movements.

?I don?t see this as being too much of an issue but certainly it?s a huge concern within the AU and was one of the reasons many high level African Union officials were officially advocating for the continued unity of Sudan.?

He, however, clarified that this referendum was something that was negotiated between the north and the south in the comprehensive peace agreement (CPA) ?so this is actually a right that was won by the south during the civil war and guaranteed by the African Union as one of the guarantors of the CPA,? he said.

A simultaneous referendum was supposed to be held in Abyei on whether to become part of Southern Sudan but it was postponed due to conflict over demarcation and residency rights.

Once the south secedes, it will take with it most of Sudan's oil reserves, and a quarter of its landmass ? something resented by many in the north.