Zambia's electoral commission halted the release of presidential election results Wednesday as voting in some districts stretched into a second day.
In a statement on its website, the chair of the commission, Justice Irene Mambilima, said "continued announcement of the results while people were still voting could unduly influence the voters."
A Zambian newspaper, the Lusaka Times, cites her as saying the delays were the result of bad weather which made some polling stations inaccessible.
Before the suspension, very early returns of less than 150,000 votes showed ruling party candidate Edgar Lungu in the lead.
Zambians voted Tuesday in a special election to replace late president Michael Sata, who died in October.
He was replaced on a temporary basis by Vice President Guy Scott, who is currently Africa's only white head of state. Scott was not eligible to run because his parents were not born in Zambia.
Earlier Wednesday, Reuters reported that Zambia's ruling Patriotic Front (PF) party candidate Edgar Lungu had taken an early lead.
Results from 14 out of 150 constituencies showed defense and justice minister Lungu, 58, had 103,634 votes, compared to 47,731 for his main rival, Hakainde Hichilema, 52, a wealthy economist from the United Party for National Development (UPND).
However, Zambia's kwacha gained 1 percent against the dollar to 6.49 as the peaceful vote eased investor jitters about stability in Africa's second biggest copper producer.
With another election due late next year when President Michael Sata's term would have ended had he not died in office, the winner will have little time to turn around a stuttering economy in one of Africa's most promising frontier markets.
Portions of this report are from Reuters.