Hurricane Irene gathered strength on Wednesday as it screamed up from the Caribbeam, leading east coast US residents to ready themselves for a possible hit over the weekend.

Irene, the first hurricane of the 2011 Atlantic season, regained force as a Category 2 storm on the five-step Saffir Simpson scale, with winds reaching speeds of 155 km per hour.

"Irene could become a major hurricane within the next day or so," the U.S. National Hurricane center said.

Irene, the ninth named storm of the June-through-November season, looks set to be the first hurricane to hit the United States since Ike pounded the Texas coast in 2008. But forecasts showed it posing no threat to U.S. oil and gas installations in the Gulf of Mexico.

The storm is forecast to approach the coast of the Carolinas on Saturday morning.

After that, the saturated New England region could be at risk from torrential rains, high winds and flooding from Irene, Federal Emergency Management Agency Administrator Craig Fugate said on Tuesday.

Major eastern cities like Washington and New York could feel some impact, the forecasts showed.

In North Carolina, Governor Bev Perdue urged residents to ensure they had three days worth of food, water and supplies.

Heavy rains continued to pelt the U.S. Caribbean territory, causing flooding and mudslides. Nearly 300,000 residents were without electricity and 58,000 were without water