JUBA, Sudan - A referendum on independence for south Sudan on Sunday raises tough questions about the legitimacy of Africa's colonial borders and sets a precedent for existing secessionist movements, analysts say.
"There is an uneasiness in Africa towards this independence because it breaks with a tradition (of borders being inviolable) and because it seems to be taking place under US pressure," says Roland Marchal, Sudan specialist and senior researcher at the Institute of Political Sciences in Paris.
"This is seen as if it were a Berlin II, with the colonial powers carving up Africa again," he said, referring to the 1885 Berlin Conference where European powers divided and colonised Africa among themselves.
A peace accord in 2005 between the mostly Arab Muslim north and the largely Christian African south ended a 22-year civil war in Sudan, with an agreement that southerners could vote for independence after six years.
Southerners are widely expected to opt for independence in Sunday's plebiscite, splitting Africa's largest country in two, and shaking the perceived permanence of the national boundaries that Africa inherited from its colonial past.
Newly independent states across the continent collaborated in 1963 to form the Organisation of African Unity -- later becoming the African Union -- which pledged to defend the territorial integrity of member states, whose borders had been drawn up by the European powers at Berlin.
"South Sudan is undeniably a precedent," said Rene Otayek, researcher at the Centre for Black African Studies at Bordeaux's Institute of Political Science.
"There has never been a referendum in an African country that allows a part of the population, a specific region, to decide whether it wants to stay within the framework of a unitary state or if it wants to break away."
Eritrea voted for independence from Ethiopia in 1993 following a 30-year war. But unlike south Sudan it had already existed as a separate state, albeit under Italian colonial rule and annexed by its southern neighbour in 1962.
"What adds to the singularity of the situation in Sudan is the international consensus on the referendum and on the pledge to respect the results of the referendum by all the parties," Otayek added.
Marchal agreed that domestic and international recognition of south Sudan's vote is key.
"The referendum is taking place within the rules of international law, with the consent of the capital and with international observers monitoring its credibility," he told AFP.
"But in terms of perception, that shows it is possible to achieve secession. And since it is possible, it may be worth fighting for."
Other regions or movements in Africa demanding some form of autonomy include Morocco's Western Sahara region, the oil-rich northern Angolan province of Cabinda, the Touareg nomads in northern Mali and Niger, the Democratic Republic of Congo's former breakaway province of Katanga and Casamance in southern Senegal.
"I am not sure south Sudan will have an immediate impact on other long-standing separatist conflicts like in Angola's Cabinda province... or the (rebel) factions in Casamance," said Alex Vines, head of the Africa programme at the London-based think tank Chatham House.
"If it goes wrong and conflict breaks out efforts at devolution... may slow down," he added.
Within Sudan itself, the referendum could also change the balance of power between the warring parties in the war-torn western region of Darfur, where recent months have witnessed heavy fighting between rebel groups and the army.
Darfur's most active group, the Justice and Equality Movement, said in August that it would demand self-determination if its nearly eight-year conflict with the government continued.