|More than 11,000 people were evacuated in the Dominican Republic ahead of the hurricane [AFP]
The United States is on a high alert as Hurricane Irene builds momentum along its path from the Caribbean towards the US east coast.
"We're going to have a very large tropical cyclone move up the eastern seaboard over the next five to seven days," Bill Read, director of the National Hurricane Center, said on Wednesday.
But Read said it was too early to be certain where Irene would hit the coastline.
Latest data showed the hurricane strengthening back into a category two storm as it moved closer to the Bahamas on Wednesday.
Irene had top wind speeds of 155 km per hour and was 650km southeast of Nassau, the Bahamas' capital.
It was expected to strengthen further before approaching the North Carolina coast at the weekend, forecasters said.
Major eastern cities like Washington and New York could feel some impact, the forecast indicated.
However, they said Irene posed no threat to US oil and gas installations in the Gulf of Mexico.
Washington, New York and other US cities are already feeling the effects of a magnitude 5.8 earthquake which struck the US east coast on Tuesday.
Irene is the ninth named storm of the busy June-through-November season and has already been blamed for one death in Puerto Rico.
It looks set to be the first hurricane to hit the US since Ike pounded the Texas coast in 2008.
Irene could disrupt a ceremony scheduled for Sunday to unveil a new memorial honouring civil rights leader Martin Luther King Jr on Washington's National Mall.
Tens of thousands of people, including US President Barack Obama, are expected to attend.
The hurricane has already hit the Turks and Caicos Islands and the southeast Bahamas with winds, rain and a dangerous storm surge.
Authorities in these areas closed airports, and banks and supermarkets shut their doors.
Government spokeswoman Andrea Been said storm surges and high waves would affect the islands into the night on Tuesday, while officials said high winds felled power lines and debris littered the streets of Providenciales.
"I pray God's blessing on us all," Hubert Ingraham, the Bahamas' prime minister, said as he urged residents to take shelter.
In the Dominican Republic, authorities said more than 11,000 people were evacuated to shelter before the storm winds brushed the island's north coast Monday night.
Quake-ravaged Haiti, which shares the island of Hispaniola with the Dominican Republic, was largely spared by the storm, although some mudslides were reported near the northern coast.