Zambians are voting in presidential and parliamentary elections following campaigning marred by clashes between rival supporters.
It is expected to be a tight race between President Edgar Lungu’s governing PF party and the opposition UPND led by Hakainde Hichilema.
For the first time, a presidential candidate must win more than 50% of the vote to avoid a run-off.
Mr Lungu won the last election by less than 28,000 votes.
Each of the nine presidential candidates has a running mate to avoid a presidential by-election if the president dies in office – which has happened twice in the last 10 years
The BBC’s Akwasi Sarpong in the capital, Lusaka, say there has been a high turnout so far at polling centres in the city.
Long, calm, orderly queues have formed and election monitors have not reported any complaints, he says.
Observers say Zambia’s struggling economy will be a key issue.
Plunging prices for copper, its main export, have closed mines and left thousands unemployed. With economic growth roughly halved, the country asked the International Monetary Fund for help earlier this year.
In addition, Zambia, like other parts of southern Africa, has been hit by a drought that the UN has described as the worst in 35 years.
The UPND (United Party for National Development) has accused President Lungu of presiding over the “collapse” of the economy. But the PF (Patriotic Front) says it has a plan to diversify the economy.
Nail polish allowed
During the last election, some women wearing nail varnish were forced to remove it before voting as polling officials said they would not be able to apply the indelible ink correctly.
But on Wednesday night, the electoral commission circulated posts on social media saying women with “painted nails and/or false nails” could vote.
A watchdog warned on Wednesday that clashes between rival political groups over recent weeks could keep some voters away.
“Escalating levels of violence may have a negative impact on the elections and reduce voter turnout,” the Zambian Elections Information Centre said in a statement.
“Political cadres have increasingly become unruly to the extent that they have shown no regard for law enforcement agents.”
On Tuesday, the head of the electoral commission, Esau Chulu, warned the two front-runners to avoid stirring unrest.
“I do not think that either of you will want to go on record as having been the two political parties who contributed to permanently denting Zambia’s record of peaceful elections,” he said.
Campaigning was suspended for 10 days in Lusaka last month after a UPND supporter was shot dead during a protest.
Zambians are casting five votes altogether – for president, MPs, mayors, local councillors and an amendment to the constitution on changes to the bill of rights.
Poll will close at 18:00 local time (16:00 GMT) and results are expected late on Friday or Saturday.
Source: BBC