efe-epaMiami (USA)

Hurricane Irma continued its westward journey across the Atlantic Ocean and threatened to bring tropical storm-force winds to the Caribbean Leeward Islands, the United States National Hurricane Center warned on Tuesday.

In its 9.00 am GMT bulletin, the NHC said Irma, a category 4 hurricane with a sustained wind speed of 240 kilometers per hour (150 mph), was situated 515 km east of the Leeward Islands, which includes the US territory Puerto Rico, the US Virgin Islands, British Virgin Islands, Barbuda and Dominica, among others.

"Irma is expected to affect northeastern Leeward Islands as a dangerous major hurricane, accompanied by life-threatening wind, storm surges and rainfall impacts. Hurricane warnings are in effect for portions of the Leeward Islands," an NHC advisory said.

"Preparations should be rushed to completion, as tropical-storm force winds are expected to first arrive in the hurricane warning area later today," it continued.

The cyclone is expected to move west at a speed of 22 kph throughout the day but is projected to shift northwest during the night, according to the NHC.

The British and US Virgin Islands as well as Puerto Rico were expecting to witness tropical-storm winds by early Wednesday, with hurricane conditions arriving later in the week.

Hispaniola, the Turks and Caicos, the Bahamas and Cuba were also on alert for dangerous hurricane conditions and the NHC advised citizens there to monitor the situation and follow official orders.

It is as yet unclear whether Irna is to make landfall on the continental US.

Irna is the fourth hurricane of the season and has come about just one week after Hurricane Harvey (later Tropical Storm Harvey) wreaked havoc on the US city of Houston, Texas.

Around 60 people died in that cyclone, while thousands of others were displaced.

Harvey was the first major hurricane to make landfall on US territory since 2005.