A 14-year-old boy was latest victim of the Haiti violence

They said both the opposition and the Lavalas Family Party of former president and current presidential candidate, Jean Bertrand Aristide have denied responsibility.

Dozens of people have been killed or wounded in recent weeks.

Opposition boycott

Mr Aristide who first won a landslide election in 1990 is expected to win easily because opposition parties plan to boycott the vote.

The opposition are protesting the disputed results of May's legislative elections which, according to international observers, were miscalculated in favour of Mr Aristide's party.

Aristide: Tipped to win the polls

The United States, Canada, and the European Union have decided not to send foreign aid or observers because the Haitian Government refused to retabulate the legislative votes.

Three of seven presidential candidates have withdrawn from the race to protest at pre-election violence.

They also accused Haiti's electoral council of favouring Mr Aristide's ruling party.

Mr Aristide, a former Roman Catholic priest, was ousted in a military coup seven months after he took office in 1991.

A US-led invasion restored him to power three years later until 1996 when Rene Preval assumed presidency.

US concern

US has criticised Haiti police for failing to contain the violence

On Wednesday the US expressed concern about the escalating violence in the Caribbean nation in the run up to the elections.

" We are concerned about the security situation and the renewed political violence, as well as an increase in violent criminal activity," said State Department spokesman Richard Boucher.

"Haitian authorities have been unable to contain violent and dangerous situations," he said.

But Haitian police spokesman Jean-Dady Simeon said: "we are working on the situation."