|Results are to be made public from December 5, with the official tally announced on December 20 [EPA]
Nearly all of the major candidates in Haiti's presidential election have called for the country's election to be scrapped amid allegations of fraud and reports that large numbers of voters were turned away from polling stations throughout the nation.
Twelve of the 18 candidates endorsed a joint statement denouncing Sunday's voting as fraudulent and called on their supporters to show their anger with demonstrations against the government and the country's Provisional Electoral Council (CEP).
The statement included all of the major contenders except Jude Celestin, who is backed by the Unity party of Rene Preval, the outgoing president.
"It is clear that Preval and the CEP was not prepared for elections," said candidate Anne Marie Josette Bijou, who read the statement to a cheering crowd that sang the national anthem and chanted "arrest Preval".
Opposition frontrunner Mirlande Manigat said the polls were fraudulent and that ballot boxes had been stuffed with votes before polls opened.
Residents of the cholera-hit country were voting for a new president, parliamentary deputies and several senators in the election.
Ninety-six contenders are competing for 11 senate seats and more than 800 more are seeking to fill the 99-seat lower house. There are also local and municipal contests.
Voting was scrapped in two northern Haitian towns following violence, local officials said, as a polling station was ransacked in Port-au-Prince, the capital.
In the towns of Acul du Nord and Trou du Nord, near Cap-Haitien, Haiti's second city, voting was abandoned after people fired volleys of gunshots into the air and went on a rampage at a voting station.
Neither official pinpointed which candidate's supporters were behind the violence.
"Men armed with machetes ransacked six polling stations - the elections were cancelled," Acul du Nord mayor Patrick Julien told the AFP news agency by telephone.
In the Tabarre district of the capital, near the international airport, "about 30 people ... went on a rampage" at a voting station after finding their names were not on a list of those registered to vote, the centre's supervisor Peteckson Renevil said.
About 10,000 people had expected to vote at the station.
The CEP had earlier acknowledged problems with the voter lists but said immediately after the candidates' news conference that the election would continue.
Even so, the united front of so many candidates could cast doubt on the legitimacy of the election, the first since a January earthquake destroyed much of the capital, leaving more than a million people still stranded in crowded tent encampments.
The call for protests could also spark violence, especially with tensions already high following a series of deadly clashes earlier this month between UN peackeepers and demonstrators who suspected them of bringing a rapidly spreading cholera outbreak.
Jean-Henry Ceant, a lawyer running for president on the "Love Haiti" ticket, dismissed the notion that the calls for protests could result in bloodshed, saying, "The only one responsible for the violence is President Rene Preval."
The Haitian government had no immediate response to the criticism.
Bijou told The Associated Press news agency that she had photos and "documentary evidence" of election fraud but walked away when asked for further details.
Voters throughout the country showed up at polling stations only to find them closed hours after their scheduled opening, or to be turned away because their names were not on lists.
At one station, even Celestin was turned away.
There were also sporadic reports of violence and intimidation, as well as a ballot boxes being stolen, its contents strewn about, in the Cite Soleil slum of the capital.
It was not yet clear whether the problems were the result of orchestrated fraud or merely disorganisation made worse by the January 12 earthquake.
Al Jazeera's Sebastian Walker, reporting from the capital, Port-au-Prince, said that it has been difficult for internally displaced Haitians to get to the polls.
Our correspondent said makeshift booths have been set up in the tent cities to facilitate voting.
Many voters and candidates said Preval, who cannot run for re-election, was trying to sway the vote in favour of Celestin.
More than 4.7 million people were eligible to vote. Results are to be made public from December 5, with the official tally announced on December 20.