The monster storm was still 110 miles (175 kilometers) away from Guantanamo late Tuesday, but "re-strengthening" to a Category 4 hurricane "as it approaches eastern Cuba," the National Hurricane Center (NHC) said in its latest advisory.

The storm took hours to cross over Jamaica, a passage over land that diminished its winds, dropping down to a Category 3 -- from the maximum level 5 -- before ramping back up.

"Melissa is expected to remain a powerful hurricane when it moves across Cuba, the Bahamas, and near Bermuda," the NHC said, adding Melissa is expected to make landfall in Cuba "as an extremely dangerous major hurricane in the next few hours."

Jamaican Prime Minister Andrew Holness declared the island a "disaster area" and authorities warned residents to remain sheltered over continued flooding and landslide risk, as dangerous weather persisted even as the hurricane's worst moved on.

Lisa Sangster, a 30-year-old communications specialist in Kingston, said her home was devastated by the storm.

"My sister... explained that parts of our roof was blown off and other parts caved in and the entire house was flooded," she told AFP.

"Outside structures like our outdoor kitchen, dog kennel and farm animal pens were also gone, destroyed."

The scale of Melissa's damage in Jamaica was not yet clear: a comprehensive assessment could take days and much of the island was still without power, with communications networks badly disrupted.

At its peak, the storm packed ferocious sustained winds of 185 miles per hour. Immediate details regarding casualty figures were not available.

Government minister Desmond McKenzie said several hospitals had been damaged, including in Saint Elizabeth, a coastal district he said was "underwater."

"The damage to Saint Elizabeth is extensive, based on what we have seen," he told a briefing.

"Saint Elizabeth is the breadbasket of the country, and that has taken a beating. The entire Jamaica has felt the brunt of Melissa."

The hurricane was the worst to ever strike Jamaica, hitting land with maximum wind speeds even more potent than most of recent history's most brutal storms, including 2005's Katrina, which ravaged the US city of New Orleans.

- 'Severely damaged infrastructure' -

Even before Melissa slammed into Jamaica, seven deaths -- three in Jamaica, three in Haiti and one in the Dominican Republic -- had been blamed on the deteriorating conditions.

Jamaica's climate change minister told CNN that Melissa's effect was "catastrophic," citing flooded homes and "severely damaged public infrastructure" and hospitals.

Mathue Tapper, 31, told AFP from Kingston that those in the capital were "lucky" but feared for fellow Jamaicans in the island's more rural areas.

"My heart goes out to the folks living on the Western end of the island," he said.

- Climate change impact -

Broad scientific consensus says human-driven climate change is responsible for intensified storms like Melissa, that are increasly frequent and bring higher potential for destruction and deadly flooding.

Melissa lingered over Jamaica long enough that the rains were particularly dire.

"Human-caused climate change is making all of the worst aspects of Hurricane Melissa even worse," said climate scientist Daniel Gilford.

The Jamaican Red Cross, which was distributing drinking water and hygiene kits ahead of infrastructure disruptions, said Melissa's "slow nature" exacerbated the anxiety.

The UN is planning an airlift of some 2,000 relief kits to Jamaica from a relief supply station in Barbados once air travel is possible.

Assistance is also planned to other impacted countries including Cuba and Haiti, UN spokesperson Stephane Dujarric told journalits.

Jamaican officials said around 25,000 tourists were in the country famed for its normally crystalline waters.