Hurricane Omar revs up off Puerto Rico

MIAMI (Reuters) - Hurricane Omar strengthened slightly on Wednesday as it bore down on Puerto Rico and the small islands of the northeastern Caribbean, the U.S. National Hurricane Center said.

Omar, which grew quickly from a tropical storm on Tuesday, had top sustained winds of 80 mph (130 kph) as it swirled about 265 miles (425 km) south-southwest of Puerto Rico, the Miami-based hurricane center said.

Additional strengthening was forecast over the next 24 hours, and Omar could become a Category 2 hurricane on the Saffir-Simpson intensity scale, with winds of at least 96 mph (155 kph), by the time it reaches the northern islands, forecasters said.

In Venezuela, the storm stopped tankers from loading crude oil at refinery facilities and knocked out power at the OPEC nation's 200,000 barrel-per-day Puerto La Cruz refinery, officials said.

While a tropical storm, the 15th of the Atlantic hurricane season, Omar had formed north of the Netherlands Antilles island of Curacao and revved up over warm Caribbean waters.

Hurricane warnings or alerts were posted for Puerto Rico, the U.S. and British Virgin Islands and other islands including Antigua and Barbuda, Anguilla, St. Kitts and Nevis, Saba, St. Eustatius, St. Martin and St. Barthelemy.

On Curacao, a small tourist island north of Venezuela, trees and lampposts were knocked down on Tuesday and power was knocked out in some areas. Stores in the capital closed due to flooding. Residents reported seeing waves up to 16 feet (5 metres) high.

There were no reports of deaths or injuries and local meteorologists said the weather was set to improve.

Omar was moving on a track that would take it over the northern Leeward Islands on Wednesday night and early Thursday. Forecasters said it could produce up to 20 inches (51 cm) of rain.