A leading opposition challenger to Democratic Republic of Congo's President Joseph Kabila called on Tuesday for the Central African state's elections to be annulled, accusing authorities of systematic fraud.
Vital Kamerhe, a former government minister, said ballots had been marked ahead of the poll in favour of Kabila, and some voters had been prevented from entering polling stations during Monday's chaotic presidential and parliamentary elections.
Three other presidential candidates urged the Congolese not to accept any results from the vote, saying widespread technical problems and fraud meant they would not be credible.
"There can be no doubt as to the scale of the fraud, deliberately planned by those in power with the connivance of the national election commission," Kamerhe wrote in a letter to Kabila, the election commission and international bodies.
"Police chased witnesses from polling stations before counting could start," he said, citing reports by international observers and others that security forces took control of voting stations in Kinshasa.
"These elections must quite simply be annulled."
At least eight people have been killed in violence linked to Monday's elections, the second since the end of Congo's 1998-2003 civil war. Authorities went ahead with the polls despite concerns of a lack of preparation.
"We have no faith in the results which will come out of these elections," read a joint statement by presidential candidates Kengo wa Dondo, Antipas Mbusa Nyamwisi and Adam Bombole.
So far, Etienne Tshisekedi, Kabila's closest challenger for president, has not joined the calls for an annulment. Kamerhe has strong support in his home region in eastern Congo but his appeal is untested elsewhere.
Before the poll, Tshisekedi did complain about irregularities and a pro-Kabila bias in the electoral commission.
Some polling stations began posting up results in Kinshasa on Tuesday even as some voters waited for the chance to cast their ballot.
A number of polling stations were burnt down or attacked on Monday as frustrated Congolese tried to find out where they should vote or were prevented from doing so by a lack of voting equipment.
Mounoubai Madnodje, spokesman for the U.N. mission in Congo known as MONUSCO, said the United Nations was still delivering electoral materials on Tuesday to some areas which have yet to vote, including the central province of Bandundu.
"We've offered our helicopters to transport materials, so yes, we're still continuing to help," he said, adding the country was generally calm.
Kabila, 40, is seen as the favourite in the single-round vote against 10 challengers. About 18,500 people are also running for 500 seats in parliament.
The electoral commission condemned violence in 14 towns and cities across the country, saying electoral material was destroyed and observers threatened.
"Any examples of witnesses being prevented from participating in the voting or counting process ... will result in the results from that polling station being annulled," it said in a statement.
Opposition strongholds including Kinshasa and the two Kasai provinces saw some of the worst disruption.
Anaclet Tshimbalanga, the president of TDH, a human rights group in West Kasai province, said at least 12 polling stations had been torched in the provincial capital, Kananga, after residents said they had found ballot papers already marked in favour of Kabila.
Highlighting the risk of the vote polarising the nation, Kazadi Nyembwe, a senior figure in Kabila's PPRD party said its supporters had been intimidated in opposition strongholds, especially the Kasai provinces.