Protesters clashed with police in Port-au-Prince while demanding election annulment [AFP]

Hundreds of protesters, demanding the annulment of Haiti's elections, have clashed with riot police in the Haitian capital, stoking tensions ahead of results expected on Tuesday.

Police fired tear gas to disperse more than 1,500 protesters when they tried to break through a barrier blocking access to the area in front of the white presidential palace, which was badly wrecked in the January 12 earthquake.

Al Jazeera correspondent Seb Walker, reporting from the capital, Port-au-Prince, said the crowds take to the streets every day calling for the process to restart but this is unlikely to happen.

Protesters and bystanders scattered as stinging gas clouds wafted through the tent and tarpaulin shelters of a large crowded camp of thousands of homeless earthquake survivors located in front of the crumbling palace.

Provisional results from the November 28 vote are due to be announced on Tuesday. United Nations peacekeepers in Haiti have been bracing for possible trouble after the polls took place amid confusion and with a cholera epidemic raging in the country.

The presidential contest featuring 18 candidates is widely expected to go to a deciding runoff, probably on January 16. UN troops and police stayed mostly out of sight during Sunday's march. The marchers also came under attack from counter-protesters who threw stones.

Vote irregularities

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Al Jazeera's Sebastian Walker reports on the violent protests in Port-au-Prince

While acknowledging problems and irregularities, the UN and international observers have cautiously endorsed the vote as acceptable and urged outgoing president Rene Preval's government and its opponents to respect the outcome.

The protesters on Sunday yelled "Arrest Preval". They accused Preval, his protege presidential candidate Jude Celestin, and electoral authorities they say are controlled by Preval, of trying to steal the elections.

Al Jazeera's Sebastian Walker reports on the violent protests in Port-au-Prince
 
"He [Preval] blocked the election and we will block the country if it continues," Satelia Saint-Louis, a 37-year-old protester, told Reuters.

Government technocrat Celestin and two prominent anti-Preval candidates, opposition matriarch and former First Lady Mirlande Manigat and popular musician Michel Martelly, are seen as the leading contenders in the race. Two of them could go through to the deciding runoff.

Jean-Henry Ceant, one of the presidential contenders repudiating the election process, condemned what he called the "electoral masquerade" and said the protests would continue "as long as necessary" until the process was annulled.

Manigat and Martelly had originally joined other candidates in denouncing fraud and calling for an annulment. But after 24 hours of intense pressure from UN officials and other foreign diplomats, they backed down and said they wanted the vote to be counted, saying they expected to be the election leaders.

Ban Ki-moon, the UN secretary-general, has urged the election candidates and their supporters to respect the law and shun violence, warning that unrest will only hinder the ongoing fight against the unchecked cholera epidemic which has killed at least 2,000 people.

Source: Al Jazeera and agencies