The US national hurricane centre said it was expected to strengthen to the next category, with top sustained winds in excess of 249kph, before passing over Jamaica towards the Gulf.
The area is home to a third of US domestic crude oil and 15 per cent of natural gas production.
Dean passed through the narrow channel between the Lesser Antilles islands of St Lucia and Martinique early on Friday, crossing from the Atlantic ocean to the warm Caribbean sea.
The hurricane, the first of what is expected to be an above-average Atlantic season, lifted the roof off the pediatric wing at Victoria Hospital in St Lucia's capital, Castries, but patients had already been moved.
|"I'm told that the coastal areas have taken a severe battering. There's debris all over Castries in the capital and flood waters on the roads" |
Leonard Montoute, deputy prime minister of St Lucia
Heraldine Rock, an ex-government minister in the former British colony of 170,000 people, said the storm ripped roofs off houses and damaged at least two banana plantations.
"In one village, telephone and power lines are down. They're strewn all over the road, trees are uprooted and are blocking the roads. In another village, a landslide has been reported, cutting off any access to the airport," Rock said.
Leonard Montoute, St Lucia's deputy prime minister, said at least two people were injured when a tree fell on their home.
"I'm told that the coastal areas have taken a severe battering. There's debris all over Castries in the capital and flood waters on the roads," he said.
The hurricane's progress is being nervously watched by energy markets, which have been skittish about hurricanes since powerful storms in 2004 and 2005, including Ivan, Katrina and Rita, disrupted oil and gas production.
Transocean, Royal Dutch Shell, Murphy Oil and other companies have pulled dozens of workers from offshore rigs as a safety precaution.
Hurricane warnings were issued for southern areas of Haiti and the Dominican Republic. Man dead
On neighbouring Martinique, an elderly man died of a heart attack during the storm and six people were injured.
Christian Estrosi, France's secretary of state for overseas territories, said the hurricane destroyed all of the island's banana plantations, which employ 10,000 of Martinique's 400,000 residents, and wiped out 70 per cent of its sugarcane farms.
Estrosi, who planned to travel to Martinique on Saturday to announce emergency aid measures, said: "In economic terms the damage is large and even dramatic. We will not leave anybody on the side of the road."
Computer models of the hurricane have fluctuated between an eventual landing as far north as Louisiana, and Belize, at the southern end of the Yucatan, but began to shift generally more to the south late on Friday.
Forecasters have predicted the six-month 2007 hurricane season would be more active than average with up to 16 named storms. An average year historically has 10 or 11 storms.