UPDATE 5-Haiti protesters rampage against election results

* Vote results contested by candidate's supporters

* Protesters set fire to ruling coalition HQ

* Haiti president, U.N., EU, Canada all appeal for calm

* U.S. embassy casts doubt on announced results (Adds statements by Martelly and EU foreign policy chief)

By Joseph Guyler Delva

PORT-AU-PRINCE, Dec 8 (Reuters) - Thousands of protesters rampaged through Haiti's capital and other cities on Wednesday, 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 the violence, which appeared to dash international hopes that the U.N.-backed elections held on Nov. 28 could create a stable new leadership for Haiti as the impoverished nation struggles to recover from a devastating January earthquake.

Port-au-Prince descended into chaos as supporters of popular musician and presidential candidate Michel Martelly, who failed to qualify for an election run-off in results announced by electoral authorities, set up burning barricades of timber, boulders and flaming tires across the city.

In a radio broadcast in Creole, Martelly said Haiti's Provisional Electoral Council had "plunged the country into chaos" with the "not good" results it had announced.

"Since then, the country has risen up to demand that the vote of the population be respected," he said. "Demonstrating without violence is the right the people have ... I am with you until the victory."

Martelly did not spell out whether he would make a formal legal challenge to the announced election results.

Protests in which some government buildings were torched were also reported in several other cities.

A local mayor in the south coast city of Les Cayes, Jean Mario Altenor, said two people were killed by U.N. peacekeepers when protesters tried to burn an election bureau. A U.N. police spokesman could not confirm how the deaths had occurred.

Haitian media also reported another person killed in protests in Cap-Haitien in the north.

Haiti's outgoing president, Rene Preval, U.N. Secretary-General Ban Ki-moon, European Union foreign affairs chief Catherine Ashton and Canadian Foreign Minister Lawrence Cannon all appealed for calm. They urged election candidates with grievances to address them through the legal channels.

"Breaking everything, destroying everything is not going to solve the problem," Preval said.

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Graphic on Haiti elections link.reuters.com/gud27q

Factbox on Mirlande Manigat [ID:nN0766033]

Factbox on Jude Calestin [ID:nN07289022]

Factbox on Haiti private investment [ID:nN07111744]

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Police fired tear gas to prevent a stone-throwing mob from reaching the offices of the Provisional Electoral Council in the Petionville district of the capital, witnesses said.

Preliminary results from the turbulent elections were announced on Tuesday. They showed former first lady Mirlande Manigat and Preval's protege Jude Celestin, going through to the January run-off. Martelly was narrowly in third place and so was excluded.

But these results flew in the face of voting returns previously cited by media and Haitian election observers that had shown Manigat and Martelly as the two run-off qualifiers.

The United States has cast doubt on the results, saying it was concerned that they were "inconsistent with" vote counts observed by "numerous domestic and international observers."

Rebuffing the U.S. statement, Preval said the electoral council was the sole arbiter of election disputes. "Just because people are protesting in the streets, the council can't just change one set of results for another," he said.

"MULTIPLE IRREGULARITIES"

Ban expressed concern about what he called "allegations of fraud," U.N. spokesman Martin Nesirky said.

The EU's Ashton said she was concerned by reports of "multiple irregularities" and "significant differences" between result projections by Haitian observers and the CEP results.

Under Haitian electoral law, candidates have 72 hours in which to formally challenge the announced results.

In Port-au-Prince, protesters set fire to the headquarters of Preval's ruling Inite coalition. Businesses and schools were closed and fearful residents stayed home.

Local police appeared to be overwhelmed by the numbers of protesters. U.N. peacekeepers of the more than 12,000-strong U.N. force in Haiti were not seen intervening in the capital.

Plumes of black smoke rose above the sprawling, crowded city, which bears the scars of the Jan. 12 earthquake that killed more than 250,000 people in the Western Hemisphere's poorest state. Haiti is also battling a cholera epidemic.

"A peaceful solution to the current situation is crucial not only to confront the cholera epidemic in the short term but also to create the conditions in the medium term for recovery and development from the earthquake," Ban's statement said.

Enraged Martelly supporters tore down, or hurled stones at election posters of Celestin and Manigat.

"It's not money that gives power, it's the people that should give power," said one protester, Lafranche Schneider.

"Hang Preval!" others yelled.

American Airlines AMR.N suspended flights to and from Haiti. The airports of Port-au-Prince and Haiti's second city of Cap-Haitien were closed, diplomats said.

"The 2010 elections represent a critical test of whether the Haitian people will determine their destiny through their vote," the U.S. embassy said in its statement.

The U.N. mission in Haiti and a joint Organization of American States/Caribbean Community election observer mission had given a cautious initial endorsement of the vote, despite acknowledging irregularities.

The Provisional Electoral Council said Manigat won 31.37 percent of the first-round votes ahead of Celestin with 22.48 percent. It put Martelly less than 1 percentage point behind Celestin at 21.84 percent.

This was on the basis of just over a million votes counted, out of a total of 4.7 million registered potential voters.

The second round has been provisionally set for Jan. 16, but the date has to be confirmed by electoral authorities. (Additional reporting by Allyn Gaestel in Port-au-Prince and Patrick Worsnip in New York; writing by Pascal Fletcher; editing by Christopher Wilson)