Irma strengthened on Tuesday into an "extremely dangerous" category five hurricane, meteorologists warned, sparking alarm and flooding alerts as it barrelled towards the Caribbean.

The monster hurricane coming on the heels of Harvey, which struck Texas and Louisiana late last month is expected to make landfall along the string of French islands including Guadeloupe late Tuesday before heading to Haiti and Florida.

The Miami-based National Hurricane Center in its 1200 GMT bulletin said Irma had strengthened to the most powerful category five, packing winds of 175 miles (280 kilometers) per hour.

The front was moving west at 14 miles (22 kilometers) per hour, and is expected to drop between four and eight inches (10 and 20 centimeters) of rain when it hits land.

"These rainfall amounts may cause life-threatening flash floods and mudslides," the NHC warned.

Irma's centre was located about 320 miles (515 km) east of the West Indies' Leeward Islands, the NHC said, urging that "preparations to protect life and property should be rushed to completion" in the region.

Schools and government offices in Guadeloupe have been ordered shut, while hospitals are stocking up on medicines, food and drinking water. People living on shorelines will be moved to safety, authorities said.

Saint Barthelemy and St Martin islands, both popular holiday destinations, are expected to be especially hard hit.

The top French official of the islands, Anne Laubies, said in Saint Martin's capital Marigot the hurricane posed the greatest threat in 20 years, with more people endangered in flood-prone areas because of a rise in population.

Source: Khaleej Times