Khartoum, Sudan (CNN) -- The United Nations on Tuesday applauded the decision by Sudan's National Election Commission to extend voting in the nation's multi-party elections by two days until Thursday.
"The U.N. also hopes that this will enable more Sudanese voters to cast their vote, especially in areas and constituencies where the technical errors caused delays to the voting process or where voters have been unable to determine which polling center they are registered in," Martin Nesirky, a spokesman for Secretary-General Ban Ki-moon, told reporters in New York.
The extension came after Sudanese and international observers complained of technical problems, including ballots being sent to the wrong polling stations and registers missing voters' names.
The main party in the south, the Sudan People's Liberation Movement, had asked for a four-day extension to the vote. The SPLM recently withdrew its presidential candidate from the race against Sudanese President Omar al-Bashir amid accusations of fraud against the ruling National Congress Party. Al-Bashir denied the allegations, prompting some parties to withdraw, partially or fully, from the election.
The voting, which began Sunday, has been scrutinized by some 750 international and 18,000 domestic observers.
Among them is former U.S. President Jimmy Carter, who on Tuesday criticized those political parties that have pulled out of the elections.
"I don't think that they should have pulled out and we and the United Nations and the United States' representatives all urged them to stay in the race," Carter told CNN.
"You have to remember two things: one is they withdrew basically after the campaign period was over at the last minute and they have known about these problems for months.
"Secondly, it's too late for them to withdraw legally. The last date was back in February, when they could have withdrawn legally. They didn't do so."
Carter and the Carter Center's Conflict Resolution Program have worked for more than a decade to find a peaceful resolution to the country's civil war.
Though he expressed doubt that the election alone would bring peace to the strife-torn nation, Carter called the voting "a major necessary step toward the implementation of the comprehensive peace agreement. And it is within that overall peace agreement that I do see finally peace coming to this country."
That overall peace agreement was brokered in 2005. The war between north and south Sudan lasted more than two decades and resulted in some 2.3 million deaths. The conflict pitted Christian and animist southerners against Muslim northerners.
A separate conflict in the western Darfur region between government militias and ethnic rebels gained more international media coverage. This conflict is regarded as genocide by the U.S. government and resulted in war crimes charges against al-Bashir, who took power in a 1989 military coup.
The vote is required before a referendum can be held next year on the south's possible secession to form an independent nation.
CNN's David McKenzie contributed to this story from Khartoum.