He stressed that the NEC has worked to correct the mistakes that occurred during the first day of the polling, adding that the process proceeded normally after correcting those errors.

"The NEC has received many reports from its committees in the states affirming that the polling was progressing acceptably after correcting the errors that occurred in the states," he said.

In response to the NEC's voting extension, a senior official of the Sudan People's Liberation Movement (SPLM) said the decision supports the SPLM's earlier demand to extend the polling days.

On Sunday, the SPLM demanded an extension of polling days due to mistakes which occurred during the first day of the process.

"If the NEC increased the number of the polling officials and their capabilities during the two days, the situation can improve," Susan Jambo, a senior election official in south Sudan, said.

"It is necessary for the NEC to conduct an investigation into the problems which occurred during the first and second days of the polling, particularly in Kaboita where the ballot box of the southern Sudan government and the legislative council was not brought," she told Xinhua in Juba, the capital of south Sudan.

She further demanded the NEC increase the voters' lists at the polling stations and direct the voters to the centers where they were registered, so that they could easily cast their votes.

The SPLM governs south Sudan in accordance of the Comprehensive Peace Agreement (CPA), inked between north and south Sudan in January 2005.

Meanwhile, the ruling National Congress Party filed a complaint with the elections commission in south Sudan over violations in the elections there.

"From the first day of the polling there were grave violations, where the people responsible for committing those violations meant to cripple the electoral process," Agnes Lokudo, secretary of NCP south Sudan sector, said at a press conference in Juba.

"Since the first day we have been observing the electoral process. Grave violations occurred today and yesterday. We have filed a complaint to the elections commission in this respect, and we will wait for its response," she added.

She explained that the violations included the arrest of NCP representatives and five observers at Kuwaji district, the expulsion of observers from the polling stations at Yerkaka, and forcing the voters to vote for the SPLM at Yae river district.

She added that there were polling stations run by SPLM members in complete absence of voters' lists.

More than 16 million Sudanese voters started casting their votes on Sunday to choose their representatives for the presidency, state governors, the president of southern Sudan and legislative councils.