Hurricane Irene has strengthened to a major storm as it bears down on The Bahamas on a path toward the eastern coast of the United States.

The National Hurricane Center said in its latest bulletin Wednesday that Irene's winds have increased to nearly 185 kilometers per hour, making it a Category Three storm on the five-point scale of hurricane intensity. Additional strengthening is forecast during the next day.

The center says Irene's core will move across the southeastern and central Bahamas Wednesday, and over the northwestern Bahamas on Thursday.

At last report, forecasters said the storm was about 540 kilometers southeast of Nassau, Bahamas, moving to the west-northwest at 15 kilometers per hour.

The storm lashed the British territory of the Turks and Caicos Islands Tuesday.

Irene is the first hurricane to seriously threaten the United States in three years and could have an impact stretching from Florida to New England — the entire east coast of the United States.

Authorities have said Irene has the potential to cause flooding in the U.S. mid-Atlantic and New England regions, where soil is saturated from recent heavy rains. They also say Irene is a very large system with tropical storm-force winds that extend 335 kilometers from the center.

The White House says officials briefed U.S. President Barack Obama on Tuesday about federal coordination with authorities in states that may be affected.

Meanwhile, the U.S. State Department issued a travel warning urging Americans to carefully consider the risk of traveling to The Bahamas and Turks and Caicos due to the hurricane.

Irene intensified into a hurricane over the U.S. territory of Puerto Rico Monday, flooding streets, knocking down trees and cutting power to about 1 million residents. There were no reports of serious injuries. President Obama declared an emergency in Puerto Rico Monday, authorizing federal aid to help local authorities recover.