Haiti and the Dominican Republic are braced for potential flooding as Hurricane Dean passes to the south after gathering force in the Caribbean.

Winds have hit 233km/h (145mph) and the storm may achieve the highest category, Five, with speeds of about 250km/h, by the time it reaches Mexico on Monday.

Dean has claimed three lives on islands in its path, and there are now fears it will directly pass over Jamaica.

Forecasters warn this could be an unusually active Atlantic storm season.

In the US, Louisiana has declared a state of emergency, though the chances of the storm hitting are slim.

Governor Kathleen Blanco took the decision amid heightened sensitivity to hurricanes since Katrina flooded New Orleans in 2005.

The neighboring state of Texas has categorized Dean as an imminent threat.

Shelters open

The hurricane is due to pass to the south of Hispaniola, the island shared by Haiti and the Dominican Republic, on Saturday.

Haiti has issued an alert for coastal communities and ordered fishing boats to stay ashore until after the weekend.

Jamaica, which fears a direct hit on Sunday, has ordered emergency shelters to be opened and Prime Minister Portia Simpson-Miller called for a halt to campaigning for the elections on 27 August.

"Let us band together and unite in the threat of this hurricane," the prime minister said.

US hurricane monitors have also urged the Cayman Islands to be vigilant.

The hurricane is due to reach the Gulf of Mexico, where the US has much of its domestic oil and gas supplies, on Monday.

Some companies have already begun shutting down production platforms and evacuating workers to the mainland.

"This storm is moving faster than the average storm," Rebecca Waddington of the National Hurricane Centre in Miami told the BBC's World Service.

"It is forecast to have a direct hit on Jamaica at a Category Four strength, which is an extremely dangerous storm [and is forecast to come] very close to the Mexican coast, near the Texas-Mexico border."

Crushed to death

Dean earlier visited destruction on the islands of St Lucia, Martinique and Dominica.

Roofs were ripped from homes and from a hospital, banana plantations were flattened and power lines torn down, while roads were flooded by torrential rain.

In Dominica, a landslide crushed a woman and her seven-year-old son while they slept in their home.

In St Lucia, a 62-year-old man was swept away and drowned when he tried to retrieve a cow from a rain-swollen river.

The threat posed by Hurricane Dean might affect the scheduled return next week of the US space shuttle Endeavour, which is currently due to land on Wednesday.

Nasa on Saturday shortened astronauts' final spacewalk by two hours to enable the shuttle to return on Tuesday if the storm appeared to threaten the Houston home of mission control.

PHOTO CAPTION

Hurricane Dean hits Fort de France, Martinique, on 18 August