Presidential candidate and Zambia's opposition leader, Hakainde Hichilema, has criticized the nation's election commission for the sluggish progress in delivering results for Thursday's vote.

"They have taken long to release the results. In the normal set up they should have been released by Friday," Hichilema, leader of the United Party for National Development (UPND) told reporters on Sunday.

"Why are they taking this long?" he asked.

Hichilema accused the Electoral Commission of Zambia (ECZ) of fraud and demanded to speak with the commission's chairman on Sunday, but was denied access to its headquarters by police.

The latest poll results put incumbent President Edgar Lungu slightly ahead with 669,960 votes, while Hichilema was close behind with 644,132, the ECZ told reporters on Sunday after 69 out of the nation's 156 constituencies had been counted.

The ECZ has denied accusations that electoral officials have tried to manipulate the vote in Lungu's favor.

Earlier, the commission hoped to deliver a final tally by early Sunday. As of yet, no explanation for the delays has been given and no new time frame has been given.

State media bias

Observers from the European Union said that despite several official requests, the election monitors were not granted access to the area where votes were being collected.

The EU monitor group praised the generally peaceful voting process on Thursday, but said state media reports had been "marred by systematic bias."

Under new election rules, a candidate must secure 50 percent of the ballots plus one vote in order to win. This means that a run-off vote between Lungu and Hichilema is possible should neither candidate secure a majority in this round.

Zambia is known for its relative stability and for being one of Africa's most successful democracies. However, the election campaign was marred by weeks of clashes between opposition and government supporters.

Thursday's elections saw Zambians choosing members of parliament, local councilors and mayors, as well as voting in a constitutional referendum to amend the nation's bill of rights.

rs/jm (AFP, dpa, Reuters)