January's referendum was enshrined in a 2005 peace deal that ended decades of civil war in Sudan between the mainly Muslim north and Christian and Animist south.
The Southern Sudan Referendum Commission said on its website that with all the votes counted, some 98.83 percent of almost four million voters had opted for independence. The turnout far exceeded the 60-percent limit needed to make the vote valid.
Mohamed Ibrahim Khalil, chairman of the commission, announced the results to a cheering crowd -- which included southern president Salva Kiir -- gathered at a memorial for John Garang, who led the south's independence fight, in the southern capital Juba.
"These results lead to a change of situation -- that's the emergence of two states instead of one state," he said.

"That change relates only to the constitutional form of relationship between north
and south. North and south are drawn together in indissoluble geographic and historic bonds."

The referendum process had raised fears of a return to north-south conflict, but Sudan's President Omar al-Bashir and his northern party have allayed these concerns by saying they would accept the south's decision to secede when early results pointed to a vote in favour of a break.

More than two million southerners died and four million were displaced in Sudan's 1983-2005 north-south civil war, which was essentially a continuation of the 1955-1972 conflict that followed independence from joint British and Egyptian rule.Kiir praised al-Bashir for taking the "bold" decision to bring peace and congratulated the dancing and singing crowd for voting for freedom.

Many issues remain to be resolved post-referendum, including the final demarcation of the north-south border, which bisects Sudan's oilfields and leaves most of the precious commodity in the south. The status of the restive border region Abyei also has to be decided.

Fighting in Abyei between northern and southern tribes claimed more than 70 lives as the referendum got underway. A separate vote on whether the region goes with north or south has been delayed.

Should all go as planned, Southern Sudan is expected to be independent by July.
While southerners are elated at the prospect of becoming a nation state, aid agencies have warned that the impoverished region faces huge challenges. Southern Sudan suffers from clashes between rival communities, has only a few dozens kilometres of paved road in a country the size of France and has appalling development indicators.
UN Secretary General Ban Ki-moon, speaking as an African Union summit opened in the Ethiopian capital Addis Ababa Sunday, said Sudan would need much support as it moved towards separation.

"Consolidating the peace in north and south Sudan will require statesmanship, wisdom,  patience and the consistent engagement and support of the international community," he said.

Al-Bashir and Kiir are due to meet in Addis Ababa Monday in a special meeting on Sudan.