Voting has been extended into a second day in the Democratic Republic of Congo’s presidential election after widespread problems led to delays in many places on Wednesday.
The head of the electoral commission estimated that at least 70% of voters had the chance to cast their ballots.
President Félix Tshisekedi faces 18 candidates as he seeks a second term in this high-stakes election.
Four of his challengers have called for the entire poll to be cancelled.
Martin Fayulu, runner-up in the disputed 2018 presidential election, described the situation as “total chaos”.
“If all the people don’t vote in all the polling stations indicated by the Ceni [Independent National Electoral Commission], we won’t accept these elections,” he was quoted as saying by Reuters after voting in the capital, Kinshasa.
The news agency reported that another presidential candidate, Nobel Peace Laureate Denis Mukwege, alleged that the “electoral fraud of the century [was] taking place”.
Mr Fayulu and Mr Mukwege were joined by two other candidates in calling for a rerun.
Millionaire businessman Moïse Katumbi said it was too soon to judge but there had been “many failures”.
The 75,000 polling stations had been due to open at just after sunrise on Wednesday across the country, but delays in the delivery of election materials or technical problems with the electronic voting machines held up proceedings in many places.
Voting continued late into the night in soma areas.
According to the Symocel observer group, nearly 60% of polling stations opened late, while 30% of voter material was defective.
Election chief Denis Kadima acknowledged that there had been problems but said that “not less than 70%” of the 44 million registered voters had the chance to cast their ballots on Wednesday.
“Those who couldn’t will vote tomorrow,” he said on Wednesday evening.
“You’ll see that the polling stations won’t be as crowded as they were today.”
Counting has started in polling stations where the voting process was completed.
The election comes after a campaign dominated by worsening conflict in the mineral-rich east.
There are some places where voting was not possible because of rebel activity.
People tallying votes
Election officials have been tallying the votes in places where the voting process has been completed
Results are supposed to be announced by 31 December.
The winner will be the candidate with the most votes, with no run-off if they fail to cross the 50% mark. The large number of challengers to Mr Tshisekedi could work to his advantage, as it may divide opposition support.
Voters have also been choosing parliamentary, provincial and municipal representatives – with about 100,000 candidates in total – in this huge country, which stretches some 2,000km (1,400 miles) west to east.
DR Congo is roughly four times the size of France, but lacks basic infrastructure – even some of its main cities are not linked by road. About two-thirds of the country’s 100 million population live below the poverty line, earning $2.15 (£1.7) a day or less.