International observers gave south Sudan's independence referendum their seal of approval on Monday and said a vote for secession was now virtually certain in their first official judgment on the poll.
Early results from last week's plebiscite suggest people from Sudan's oil-producing south overwhelming voted to split away from the north after decades of civil war.
Observers from the Carter Center and the European Union both said the vote had been credible, an endorsement that moved the region a step closer to independence.
The European Union election observation mission assess the voting process of the Southern Sudan Referendum credible and well-organised in a mostly peaceful environment, a preliminary statement seen by Reuters said.
Former U.S. President Jimmy Carter's mission said a number of irregularities had not undermined the legitimacy of the referendum, which hopes to end a violent cycle of bitter north- south conflict in Africa's largest country.
The (Carter) Center finds that the referendum process to date is broadly consistent with international standards for democratic elections and represents the genuine expression of the will of the electorate, its statement read.
In the southern capital Juba, six centres each had more than 2,500 votes for secession compared to a maximum of just 25 votes for unity.
Around 97 percent of southerners voting in Egypt chose separation, compared with just 2 percent for unity, the poll's organising commission said on Monday.
Based on early reports from vote counting centres, it appears virtually certain that the results will be in favour of separation, Carter Center observer and former Tanzanian prime minister Joseph Warioba told reporters in Khartoum.
Preliminary results are expected by the end of the month and south Sudan would become an independent nation on July 9, according to the terms of the 2005 north-south peace deal that promised the referendum.
The E.U. mission said soldiers and intelligence officers had been stationed too close to voting centres in a few cases, raising the risk of intimidation.
Observers had raised concerns before the vote that there was a lack of informed discussion in the north about secession and in the south about unity.
We were concerned that there wasn't a conducive environment for campaigning for unity in the south, similarly for secession in the north, the Carter Center's Sudan director Sanne van der Bergh told journalists.
Illustrating the strength of public emotion in favour of secession in the south, some voters expressed anger that even one person would vote for unity.
I'm annoyed -- why are they voting for unity? I thought that we didn't have such people in the south -- they are not southern Sudanese, student Victor Ajuot, 25, said in Juba.
Senior north Sudanese official Ibrahim Ghandour told Reuters last week the voting, which ended on Saturday, had been broadly fair, allaying fears that disagreements over the outcome would reignite conflict.
Sudan's north-south civil war has simmered since 1955, claiming an estimated two million lives.