Zambia's electoral commission has resumed the counting of votes from Thursday's presidential, parliamentary and local elections after it was halted over alleged attacks on polling staff.

The authority paused the process nationwide,expressing concern about reports of violence that had "resulted in the theft of marked ballot papers in ballot boxes".

President Hakainde Hichilema is seeking a second five-year term. Brian Mundubile is the main opposition candidate among 13 challengers.

The electoral commission has set itself the target of announcing the results by the end of Sunday.

In its Friday evening update, the commission said that following a review of the situation and consultations with relevant law enforcement agencies, "the security threat to the electoral process has been contained and the necessary measures have been put in place to enable the process to continue".

Counting initially got under way immediately after polls closed on Thursday, but no official results had been declared when the halt came into effect.

Earlier on Friday, Mundubile expressed "grave concern" over delays in the announcement of presidential results, warning that the delay could create opportunities for interference or manipulation.

He cited what he described as "deeply troubling reports" from several areas, including alleged military involvement at tallying centres and allegations concerning the movement of ballot boxes.

He called for the immediate publication of results polling station by polling station, protection of the chain of custody and investigations into the reported incidents. He also said that his own party's tabulation of the results showed that he had won.

Hichilema also issued a statement urging Zambians to "remain peaceful, patient and patriotic as we await the official outcome from those entrusted with managing the vote".

Polling day was largely peaceful, with queues reported in many areas and only isolated delays. Along with electing a president and MPs, the more than eight million registered voters had the chance to choose a new parliament and local councils.

Thursday's vote was seen as a test of Zambia's reputation as one of Africa's most stable democracies, amid concerns that political freedoms are being undermined.

Despite 14 candidates being on the presidential ballot paper, the contest was largely seen as a two-horse race between the incumbent and his main challenger, Mundubile - running on the banner of the National Reconciliation Party for Unity and Prosperity (NRPUP).

Hichilema is credited with steering Zambia through a difficult economic climate, but his popularity was dented as many people said their circumstances have not improved. Mundubile hoped to capitalise on that dissatisfaction.

Mundubile is a former minister in the Patriotic Front (PF) government that ruled from 2011 to 2021, with his alliance drawing support from backers of the late former President, Edgar Lungu.

Lungu died more than a year ago, and his body remains unburied in South Africa, amid a bitter dispute between Lungu's family and Hichilema, which has heightened political divisions in Zambia.

Hichilema, 64, won the 2021 election on his sixth attempt and is betting on job creation and an ambitious infrastructure drive to secure a second and final term.

The election was seen as a referendum on his economic record, which has boasted debt restructuring, currency strengthening and lowered inflation.

But his United Party for National Development (UPND) government has also been criticised by Amnesty International for restricting rights and freedoms in the run-up to this election, an accusation that Zambian authorities have yet to comment on.

Civil society monitors reported mostly orderly voting alongside some incidents of delays and procedural issues. International observers are present.

Mwiche Nalupumbwe, 26, was among hundreds who braved Thursday's morning chill to queue at polling stations well before they opened.

"Zambians are frustrated, and this election is a 50-50, that is why we are all here early to make the change," he told the AFP news agency.

"I voted for HH because he cares about us," James Phiri, a 29-year-old student at the University of Zambia, told the Reuters news agency, using a common nickname for the president.

"Things are better after he re-introduced meal allowances," he said.

Samuel Chitendwe, a 47-year-old welder and father of four, said he voted for Mundubile.

"I have just come from firing someone. We are tired of stories about economic progress," he told Reuters.

If no presidential candidate gets more than 50% of the vote a run-off must be held within 37 days.