Britain has bolstered the funds available for tackling the aftermath of Hurricane Irma as it continues to lay waste to the Caribbean.

Theresa May announced £32 million has now been released to assist the relief effort, up from £12 million, after devastation was unleashed on British overseas territories.

The military has parachuted a task group of experts into the affected areas of the Atlantic to provide support while the Royal Fleet Auxiliary (RFA) Mounts Bay ship is transporting supplies.

At least six people are known to have died and the island of Barbuda has been left “barely habitable” after the category-five storm flattened swathes of the Caribbean.

Speaking after a meeting of the Government’s emergency Cobra committee, the Prime Minister said: “No-one can fail to be affected by the absolutely desperate plight of people in the Caribbean who have been hit by Hurricane Irma and my thoughts and prayers are with all those affected, particularly with British nationals in the overseas territories of Anguilla and the British Virgin Islands.

“It has been devastating, it is the most powerful storm to hit the Atlantic, it has brought devastation in its wake, it has destroyed buildings and infrastructure, but it has had such an impact on people’s lives because it has seen people’s livelihoods completely destroyed and, of course, some people are missing and some will have lost loved ones.”

“We have taken action, we moved swiftly, there are people on the ground, £32 million has been released.”

She added the Government would “continue to do what is needed and provide what is necessary” as the storm progresses towards the US.

Addressing concerns about the speed of Britain’s response to the unfolding crisis, Mrs May said both humanitarian workers and RFA Mounts Bay had been “prepositioned”.

Defence Secretary Sir Michael Fallon added the military vessel is “already at work” clearing roads and helping to restore power.

He said: “We’re there and we’re helping, but obviously this is a huge challenge, more help is going to be needed and that’s what we’ve authorised today.”

The storm destroyed nearly all buildings on the island of Barbuda on Wednesday, killing a two-year-old child as a family tried to escape.

French Prime Minister Edouard Philippe said four people were confirmed dead and about 50 injured on the Caribbean island of St Martin.

The death toll was lower than one given earlier by France’s interior minister, who indicated eight people had been killed on French Caribbean territories.

One death was also reported on the nearby island of Anguilla, a British overseas territory that was among the first islands to be hit.

Where Hurricane Irma has already beenWhere Hurricane Irma has already been (PA Graphics)

The island’s airport, hospitals, shelters and schools suffered extensive damage and 90% of roads are impassible, according to the Caribbean Disaster Emergency Management Agency.

It also reported “major damage” to houses and commercial buildings in the British Virgin Islands.

More than a million people were left without power on Puerto Rico after the hurricane passed overhead while in Barbuda about 60% of the island’s approximately 1,400 people are now homeless.

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

Sir Richard Branson, who has been camped out on his private island Necker, described the devastation caused by the hurricane.

Writing on his blog, the billionaire businessman said: “I have never seen anything like this hurricane.

“Necker and the whole area have been completely and utterly devastated. We are still assessing the damage but whole houses and trees have disappeared. Outside of the bunker, bathroom and bedroom doors and windows have flown 40ft away.”

Sir Richard said Virgin Atlantic’s Antigua flight on Thursday had been loaded with essential items to help the recovery effort, including blankets and bottled water.

“We will do whatever we can to support and assist our local community through this extremely testing time,” he added.

Airports in the Bahamas were shutting down as the massive storm approaches while Florida is on high alert, with the storm forecast to hit at the weekend.

Atlantic storm outlook. See story WEATHER Hurricane. Editable files from PA Graphics

Thousands of British tourists believed to be holidaying in the Caribbean have been urged to follow evacuation orders while states of emergency have been declared in Puerto Rico, Cuba and Florida.

British litigation lawyer Olga Osadchaya described how her home on Tortola had been completely gutted by the storm.

The 33-year-old, who has lived on the island for four months, told the Press Association: “The damage is horrific. There’s barely any connection. There’s about 12 of us huddling around one miraculous wi-fi connection. A window literally exploded outwards in front of my eyes.

Royal Fleets Auxiliary ship Mounts BayRoyal Fleets Auxiliary ship Mounts Bay (Dez Wade/MoD/Crown Copyright/PA )

“We hid in the back room holding a piano across a pounding door – then the calm of the eye came and we relocated to another house next door which had proper hurricane-proof windows.”

Hurricane Irma’s winds have fallen slightly to 175 mph (285 km/h) and the storm is forecast to remain at category four or five over the next few days.

As thousands of Florida residents begin evacuating and others board up their homes, President Donald Trump urged people to “be careful, be safe”.

In a tweet on Thursday, Mr Trump remarked that Irma “is raging but we have great teams of talented and brave people already in place and ready to help”.