Hurricane Tomas weakened to a tropical storm after it lashed Haiti's crowded camps of earthquake survivors and coastal towns, triggering flooding and mudslides that killed at least seven people.

Haitian authorities, struggling with the devastation of January's earthquake and a deadly cholera outbreak, believed the worst from Tomas was over, but meteorologists warned of more rain for parts of Haiti, theDominican Republic, the Bahamas, Puerto Rico and the Turks and Caicos.

Houses on Port-au-Princes' hillsides destroyed by mudslides and heavy flooding at some of the city's main thoroughfares.

In the capital Port-au-Prince, still scarred by the January 12 earthquake that killed a quarter of a million people, hundreds of thousands of homeless survivors huddled under rain-drenched tent and tarpaulin shelters in muddy encampments.

The United Nations and relief agencies have gone on maximum alert to prepare for the possibility of another humanitarian catastrophe in the Western Hemisphere's poorest nation although the UN Office for the Coordination of Humanitarian Affairs said the storm could have dealt a far worse blow.

The United Nations said the storm almost certainly will exacerbate a cholera epidemic that has killed 442 people and sickened more than 6,700 so far.

With threats of floods and the spreading cholera epidemic, Haiti faces major disruption just weeks before presidential and legislative elections on November 28. Electoral officials have not postponed the vote.