|The outbreak of violence caused officials to close the country's airports [AFP]
Thousands of protesters have rampaged through the capital, Port-au-Prince, and other cities, hurling stones and wrecking property in a wave of unrest against election results they say were rigged by the ruling government coalition.
At least two people were killed in Wednesday's riots, which appeared to dash international hopes that the UN-backed elections held on November 28 could create a stable new leadership for Haiti - an impoverished nation struggling to recover from a devastating January earthquake.
Port-au-Prince descended into chaos as supporters of Michel Martelly, a popular singer and presidential candidate who failed to qualify for an election runoff according to preliminary results announced by electoral authorities, set up burning barricades across the city.
Protesters also set fire to the main offices of the ruling party.
The outbreak of violence caused officials to close the country's airports as several major airlines cancelled their flights to and from Haiti.
The demonstrators took to the streets after officials had announced that Jude Celestin, representing the ruling party, will stand in the upcoming presidential runoff vote.
Martelly had trailed Celestin by about 6,800 votes - less than one per cent, according to the preliminary results.
"If they don't give us Martelly and [Mirlande] Manigat [in the second round], Haiti will be on fire," Erick Jean, a protester, said.
"We're still living under tents and Celestin wastes money on election posters.''
The singer, known as "Sweet Micky", has until December 20 to formally lodge a complaint with the
Al Jazeera's Imtiaz Tyab reporting from the Haitian capital said the violent protests have spread to more areas outside Port-au-Prince, with many people expressing anger over the election results.
"Many people say they are not just frustrated with the electoral system or the vote but with the current government, especially over its poor handling of the aftermath of the January earthquake."
Violence was also reported in Cap-Haitien on Tuesday as well as the southern city of Les Cayes, where residents said government buildings had been attacked and set on fire.
Mirlande Manigat, the former first lady, will advance to the runoff and stand against Celestin, after no candidate gained more than the 50 per cent required to win in the first round.
The results announced late on Tuesday were immediately questioned in Haiti and abroad.
Much of the concern centred around conflicts between the announced results and those reported recently by the National Observation Council, a local election monitoring group financed by the European Union, which said that Celestin would be eliminated.
The US embassy said in an e-mailed statement: "The Government of the United States is concerned by the Provisional Electoral Council's announcement of preliminary results ... that are inconsistent with the published results of the National Election Observation Council'' as well as US observers and vote counts by domestic and international observers".
Official election observers have said a third candidate might be included in the January 16 runoff if the electoral council decides the first-round vote was close enough, even if the constitutionality of such a move is debatable.