Officials across the north-eastern Caribbean have cancelled flights, closed schools and urged people to shelter indoors as Hurricane Irma barrels towards the region after strengthening to a Category 5 storm.

States of emergency were declared in Puerto Rico, the US Virgin Islands and all of Florida while people on various Caribbean islands boarded up homes and rushed to find last-minute supplies, forming long lines outside stores and filling stations.

Irma’s maximum sustained winds increased to near 175mph early on Tuesday, the US National Hurricane Centre said.

The storm was centred about 270 miles east of the Leeward Islands and was moving west at 14mph.

Authorities warned that the storm could dump up to 10in of rain, cause landslides and dangerous flash floods and generate waves of up to 23ft.

Hurricane Irma's likely pathHurricane Irma’s likely path (PA Graphics)

“This is not an opportunity to go outside and try to have fun with a hurricane,” US Virgin Islands governor Kenneth Mapp warned. “It’s not time to get on a surfboard.”

The storm’s centre is expected to move near or over the northern Leeward Islands late on Tuesday and early on Wednesday, the hurricane centre said.

Residents on the US East Coast were urged to monitor the storm’s progress in case it should turn northwards towards Florida, Georgia or the Carolinas.

“This hurricane has the potential to be a major event for the East Coast. It also has the potential to significantly strain Fema (Federal Emergency Management Agency) and other governmental resources occurring so quickly on the heels of (Hurricane) Harvey,” said Evan Myers, chief operating officer of AccuWeather.

In the Caribbean, hurricane warnings were issued for 12 island groups, including the British Virgin Islands, where the governor urged people to evacuate the tiny island of Anegada if they could.

People in the US territory of Puerto Rico braced for electricity outages after the director of the island’s power company predicted that storm damage could leave some areas without electricity for four to six months.

But “some areas will have power (back) in less than a week”, Ricardo Ramos told radio station Notiuno 630 AM.

The utility’s infrastructure has deteriorated greatly during a decade-long recession, and Puerto Ricans experienced an island-wide outage last year.

Puerto Rico and the US Virgin Islands expect 4in to 8in of rain and winds of 40-50mph with gusts of up to 60mph.

A hurricane warning was posted for Antigua and Barbuda, Anguilla, Montserrat, St Kitts and Nevis, St Martin, Saba, St Eustatius, St Maarten and St Barts, Puerto Rico and the US and British Virgin islands.

A tropical storm warning was in effect for Guadeloupe and Dominica.