At least 19 people have died in Jamaica as a result of Hurricane Melissa, Information Minister Dana Morris Dixon has said, as search and rescue efforts continue and authorities try to get aid to hard-hit areas.

The hurricane, one of the most powerful to strike the Caribbean, has also killed at least 30 people in Haiti, officials said.

In Jamaica, "there are entire communities that seem to be marooned and areas that seem to be flattened," Dixon said, adding there are "devastating" scenes in western regions.

Electricity remains out to most of the island and as people try to salvage damaged homes and belongings from floodwaters and mud, many thousands are growing increasingly desperate for aid.

There are parts of the country that have been without water for several days and food is growing increasingly scarce.