The BBC's Stephen Sackur: "The next move is difficult to predict"

Up to two million people have left their homes as they try to escape the worst effects of the storm.

US President Bill Clinton cut short a trip to New Zealand and declared a federal state of emergency in both states because of the approaching hurricane.

Latest reports say Floyd, one of the most powerful storms to hit the region this century, is veering to the northwest and slightly reducing in intensity. But forecasters are warning it is still very dangerous and capable of causing considerable damage.

At 2100 GMT (1700 EST) Hurricane Floyd was positioned 235 miles (380 km) southeast of Cape Canaveral, roughly midway along Florida's eastern coastline, and heading northwest at about 12mph (19kph).

At current estimates, it should remain off the Florida mainland, making landfall in South Carolina by midnight on Wednesday.

Bahamas battered

Earlier, the hurricane swept through the Bahamas, bringing down trees and powerlines and flinging debris into buildings.

The BBC's Stephen Gibbs reports: "This may be the biggest evacuation in American history"

Terrified motorists were rocked in their cars and trees were torn from the ground as the centre of the storm passed over Arthur's Town on North Cat Island on Tuesday.

Phone links between the capital, Nassau, and outlying areas were said to have been severed.

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A few mph more and Floyd would hit the top of the hurricane scale

Schools and shops were shut down and residents fled from their boarded-up homes as surging seas reached more than 20ft higher than normal tide levels.

Weather experts said that if Floyd's winds had been just a few miles per hour harder, it would have been classified as a category five storm, the most powerful of hurricanes.

Florida residents flee

Meanwhile, in Florida, US authorities declared a state of emergency and warned nearly two million residents to leave coastal areas as far north as North Carolina.

Over a million people have evacuated from Florida

The Florida Emergency Operations Centre issued a 400-mile hurricane warning and hundreds of thousands of people continued a rush to buy up hardware and board up their properties before fleeing.

Experts also warned that Floyd still had the potential to wreak as much havoc as 1992's Hurricane Andrew, which killed at least 26 people and caused more than $25bn worth of damage.

Resorts close

As authorities co-ordinate the civil emergency, Florida's tourism industry shut down with two of the major Orlando attractions, Disney World and SeaWorld, closing.

A deserted Disneyworld as the resort shut down for the first time

Almost every flight in or out of southern Florida was cancelled while the military sent aircraft inland and ships out of port to ride out the storm.

In Charleston, South Carolina, authorities told the crews of civilian cargo ships to prepare to leave port.

National Guard forces have been put on alert across three states as authorities lifted tolls on major roads away from the coast to help get the population out as quickly as possible.

Nursing homes in South Carolina area also reported to be moving residents inland.

Only a skeleton crew has remained at the low-lying Kennedy Space Centre at Cape Canaveral and three of Nasa's space shuttles were moved to their hangar - designed to only withstand winds of up to 105 mph.

The last time Nasa took such precautions was during Hurricane Erin in 1995.