A number of Hakainde Hichilema’s supporters in the United Party for National Development were arrested and bundled into a police van, an AFP correspondent saw.
Police initially asked the supporters to disperse but one of them shouted back at the officers, who then drove them off with batons and tear gas.
Hichilema is seen as the main challenger to ruling Patriotic Front party candidate Edgar Lungu in the contest to replace former president Michael Sata who died in office last October.
At stake is the remaining year and a half of Sata’s five-year term in the copper-rich but impoverished southern African nation.
Announcing that voting would be extended, electoral officials said boats and ox-wagons would be deployed to get ballot papers to parts of the country hit by torrential rains.
“We faced unprecedented challenges in ferrying voting materials to most parts of the country because of the heavy downpour that the country has experienced in the recent days,” said Priscilla Isaac, director of the national electoral commission.
“Voting in some polling stations started today (Wednesday) and will continue tomorrow (Thursday),” Isaac told journalists.
Some 7 000 voters in 12 polling stations across the country were expected to finally be able to cast their ballots on Thursday.
The extension meant the authorities to once again suspended the announcement of the results of the hotly-contested presidential election race to replace president Michael Sata who died last year.
Just 13 constituencies out of 150 had been tallied before the release of results was suspended, with Lungu leading in 11 of those with 92 026 votes while Hichilema trailed with 44 902 votes.
A results update was expected Thursday morning.
A planned airlift of ballot papers and polling officers to remote villages was disrupted on Tuesday, the first day of voting, by thunderstorms which grounded flights.
The delay in the delivery of polling materials led Hichilema, a wealthy businessperson, to cry foul and allege fraud.
He also complained about the extension of voting, the shifting of some polling stations and alleged acts of violence by ruling PF supporters.
The head of a regional observer team, South African Foreign Minister Maite Nkoana-Mashabane commended the electoral body for holding a “generally peaceful” vote under “challenging” conditions.
A group of southern African NGOs said in a statement the poll was “credible based on the voting day and generally the election was free and fair”.
In the absence of reliable opinion polls, analysts hedged their bets.
“It’s a two-horse race,” said Oliver Saasa, chief executive of Premier Consult, a business and economic consultancy firm. “It’s quite clear this is a very closely run race.”
Hichilema’s camp is perceived to have received a boost from in-fighting within another major opposition party, the Movement for Multiparty Democracy (MMD).
Lungu’s PF, meanwhile, went into the vote badly fractured by a bitter power struggle after Sata’s death in October.
With ideological differences between Zambia’s political parties difficult to pin down, voting patterns are often determined by personalities and ethnicity rather than issues.
Despite growth-oriented policies and a stable economy over the past few years, at least 60% of Zambia’s population of 15-million lives below the poverty line, according to World Bank figures.
About 5.2-million people were eligible to vote, but turnout is expected to be low, partly because of the weather. – AFP