Protesters erected burning barricades in the capital of Haiti Port-au-Prince last night and stormed a luxury hotel to demand results from the country's nearly week-old election.
The riots broke out as ex-President Rene Preval fell further below the 50 per cent needed to win the presidency.
Witnesses said UN peacekeepers fired into a crowd of protesters in Tabarre, just north of Port-au-Prince, killing at least two people, but a UN spokesman said the troops only shot into the air.
The peaceful atmosphere that surrounded last Tuesday's balloting, the first since Jean-Bertrand Aristide was ousted by an armed revolt two years ago, began to unravel six days later amid charges that election officials were tampering with results to prevent Mr Preval from taking a first-round victory.
"No vote will be stolen," interim Prime Minister Gerard Latortue told Haitians in a television address following a day of unrest. "We ask everyone to go back home, to stay calm and the results will be published."
Like Mr Aristide, Mr Preval is viewed as a champion of the Caribbean country's poor masses, most of whom live on $1 a day, but he is distrusted by the small and wealthy elite that helped push Mr Aristide from office on February 29th, 2004.
Across the capital, traffic ground to a halt, schools shut down and the UN told its civilian employees to stay home. Demonstrators piled wrecked cars and tree branches in the streets after the latest results.
With 90 per cent of the vote counted, the Provisional Electoral Council said Mr Preval had 48.7 per cent.