Hurricane Irene has strengthened into a Category 3 storm as it passes over the Bahamas, battering the holiday hotspot with 115mph winds.

Irene, the first hurricane of the 2011 Atlantic season, is expected to intensify further over the coming days before making landfall in the U.S. at the weekend.

The National Hurricane Center in Miami has warned of an 'extremely dangerous' storm surge as Irene gains more strength before hitting the East Coast of America, an area already affected by a 5.8-magnitude quake on Tuesday.

Rough seas: The Dominican Republic has been battered by high winds and huge waves as Irene passes through

Forecasters believe Irene will hit the state's Outer Banks - a string of islands which are a popular with summer holidaymakers - region on Saturday afternoon and say the impact could be widespread.

The islands are braced for an evacuation if necessary, using boats and the bridges which link them to the mainland.

The roughly 200-mile stretch of fragile barrier islands off the state's coast offer pristine beaches, attracting thousands of tourists each year. 

Even if the center of the storm stays offshore, the hurricane could lash cities including Washington and New York with winds and rain and cause coastal flooding and power outages.

'Irene will be a large storm, impacting areas far from the storm center track,' hurricane expert Jeff Masters of private forecaster Weather Underground wrote in his blog.

But as forecasts of more than four days can have a margin of error of up to 200 miles, emergency officials have warned the entire U.S. East Coast to be on the alert for what they describe as a large and potentially dangerous storm.

Path of destruction: The hurricane is expected to slam into the East Coast of the U.S.

The warning comes just a day after the area was hit by a 5.8-magnitude earthquake rattled Washington and cities from the Carolinas to Canada on Tuesday.

A high-pressure system has altered the hurricane's route meaning it is unlikely to affect Florida as much as first predicted.

But NHC meteorologist Jorge Aguirre said: 'There is still a lot of uncertainty.

'These things are often unpredictable. I would not say Florida is completely off the hook just yet. It’s going to be a very close call.'

Irene is currently centred about 335 miles southeast of Nassau in the Bahamas and is moving west-northwest near 9mph.

The hurricane has already wrought destruction across the Caribbean, with half of the island of Puerto Rico losing power and one woman reported dead.

Wind and rain damage have also hit the Dominican Republic and Turks and Caicos and a state of emergency was declared in the British Virgin Islands.

Sir Richard Branson's holiday home on Necker Island was also destroyed when lightning, caused by the stormy weather, struck the Balinese-style property, causing a fire.