Organizers of southern Sudan's independence referendum say voter turnout will reach the 60 percent mark needed to make the poll valid.
A member of the referendum commission, Suad Ibrahim Eissa, said in a statement Wednesday that turnout will "exceed" the 60 percent threshold.
A senior official with the south's ruling party, the Sudan People's Liberation Movement, said the threshold of nearly 2.3 million voters was reached on Tuesday.
Nearly 4 million people registered to vote in the referendum. The weeklong poll is expected to result in southern Sudan choosing to separate from the north.
The United Nations says preliminary results are expected by February 2, with final results to follow within about two weeks.
Voting has been largely peaceful, although there have been deadly tribal clashes along the north-south border in the disputed Abyei district.
Control of the oil-rich Abyei region is one of several issues the north and south still must resolve.
Dignitaries from around the world, including former U.S. president Jimmy Carter and ex-U.N. secretary-general Kofi Annan, are in Sudan to observe the vote.
Mr. Carter told VOA that he has been assured by Sudanese President Omar al-Bashir that he will accept the results and help the south regardless of the outcome. He expressed confidence the referendum will be transparent and credible.
The independence poll is part of the 2005 peace deal that ended 21 years of war between Sudan's Muslim-majority north and the mainly Christian and animist south.