Relief efforts are under way on the British islands devastated by Hurricane Irma as a second 'extremely dangerous' storm threatens the Caribbean.

Medical supplies and other aid are being flown from the UK to the areas worst affected by Irma following a £32 million pledge from the British Government.

The death toll from Irma has risen to 20 - with a further four people believed to have died on the British Virgin Islands.

A spokesman for the Ministry of Defence said aircraft carrying around 230 personnel, made up of engineers, marines and medical specialists, will take rations and medical supplies to places affected including Barbados and the British Virgin Islands.

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Members of 24 Commando Royal Engineers were pictured landing in the British Virgin Islands this morning after landing in an RAF C17 plane

Officials said it has been difficult to gauge the extent of the damage because communication lines have gone down

But the Department for International Development (Dfid) has sent advisers to the area to assess the wreckage.

More than 200 Royal Marines, along with engineers, specialists, medical supplies, and aid, including emergency shelter kits, rations and clean water, have been flown out to the region.

The Prime Minister also sought to give assurances to the British territories that the Government's support would include a focus on long-term rebuilding.

She said: 'I give them this commitment – I recognise that our immediate concern is ensuring the support is there and every effort is there as this hurricane is devastating these islands, but at the Cobra today I also ensured that a piece of work was being put in place, already started, on long-term planning.'

RFA Mounts Bay has helped to restore power and communications as well as clear the airport runway in Anguilla, and will next provide relief in the British Virgin Islands, Dfid said.

HMS Ocean is due to take equipment and aid supplies from Gibraltar to the Caribbean on Monday.

Members of 24 Commando Royal Engineers were pictured landing in the British Virgin Islands this morning after landing in an RAF C17 plane.

Mounts Bay's Commanding Officer Capt Stephen Norris RFA said last night: 'My people worked tirelessly throughout the day with determination and flexibility to support the Governor and the people of Anguilla.

'Although Anguilla suffered extensive damage, normal signs of life were returning - some roads open and the local population beginning a recovery and clear-up operation.'

The Chinook helicopter was loaded with equipment ahead of its meeting with the HMS Ocean task group, which will provide aid to the Caribbean

HMS Ocean is due to take equipment and aid supplies from Gibraltar to the Caribbean on Monday. Pictured: Royal Engineers arriving with aid today

Medical supplies and other aid are being flown from the UK to the areas worst affected by Irma following a £32 million pledge from the British Government

Buckingham Palace said the Queen will be making a significant personal donation to the Hurricane Irma appeal organised by the British Red Cross.

The government of the Turks and Caicos Islands, which were 'pummelled' overnight, declared a national shutdown as the hurricane continued its destructive path towards America.

Forecasters said another storm - Hurricane Jose - could affect already-hit areas with the British Virgin Islands on tropical storm watch, and the Commonwealth islands of Barbuda and Antigua and British territory of Anguilla on hurricane watch.

The British Virgin Islands, which saw houses reduced to their foundations and many roads impassable in the wake of Irma, has already declared a state of emergency.

Buckingham Palace said even the Queen will be making a significant personal donation to the Hurricane Irma appeal organised by the British Red Cross. Pictured: Royal Engineers in the British Virgin Islands

Theresa May's spokeswoman dismissed criticism that the UK lagged behind France and the Netherlands in taking care of its territories in the path of the hurricane

RAF Oldiham personnel loading equipment in the Chinook as part of Op Ruman

As the hurricane sweeps through the Caribbean, the RAF load equipment as part of an aid mission

Images posted on social media showed entire structures razed to the ground, with debris scattered across the streets.

There has been criticism of the Government's response to Irma, the most powerful hurricane ever to hit the Atlantic, with some saying more should have been done to prepare for the devastation.

Labour MP Virendra Sharma, who sits on the International Development Committee, said there had been a 'lack of vision and lack of proper response', despite indications the hurricane was coming.

But Theresa May's spokeswoman dismissed criticism that the UK lagged behind France and the Netherlands in taking care of its territories in the path of the hurricane.

Aftermath: The hurricane has so far killed at least 24 people across the Caribbean and laid waste to vast areas. Pictured: The British Virgin Islands

Hurricane Irma smashed into the British Virgin Islands as a Category 5 storm before weakening to a Category 4 storm

The Government is working with the US authorities to ensure 'everything can be done' before the storm arrives, she said.

Meanwhile British police officers will be deployed as part of the efforts to step up support to the Caribbean islands left devastated by Hurricane Irma.

Almost 300 military personnel have left the UK as part of Operation Ruman, the Ministry of Defence (MoD) said.

The NPCC announced that British police officers will provide support to the British Virgin Islands force as part of the relief effort.

Paradise lost: This car was flipped on its side in the British Virgin Islands and almost completely destroyed by the devastating winds of Hurricane Irma

It said two members of the UK police cadre, who support the military in times of international crisis, flew out yesterday, while a further 53 British officers from 14 police forces are due to leave from RAF Brize Norton in co-operation with the MoD.

The officers will support the local police force to maintain law and order, as well as helping to find missing people, including British nationals, the NPCC explained.

The organisation's lead for international policing, Chief Constable Andy Marsh, said: 'We received offers of support from officers across the country as soon as this crisis began.

'These officers, and the many others who volunteered, signify our commitment to help those in need and humanitarian instinct of the British police force, no matter where in the world.'

Wreckage: Many boats on the British Virgin Islands have been destroyed by the storm

Irma was first classified as a tropical storm on August 30 and rapidly intensified over the following days. Winds reached a peak of 130mph but soon became the strongest for more than a decade when sustained winds peaked at 185mph.

Thousands of British tourists believed to be in the Caribbean have been warned to follow evacuation orders while some have been advised to stay in their hotel rooms.

Holiday firms said they are monitoring the situation and some have cancelled flights or offered to amend bookings for those due to travel to affected areas in the coming days.

Hurricane Irma's trail of destruction

In Fort Lauderdale, Erik Petersen, 40, described the atmosphere as 'pretty tense' – adding that there was much more worry than last year, when the Sunshine State braced itself for Hurricane Matthew.

The dual American-British citizen told the Press Association: 'People aren't just talking about this as a hurricane, they're talking about it as the hurricane.

'I've had a few people ask if I'm considering going somewhere else in Florida, but this thing's the size of Texas. Roads are clogged, hotels are full, gas is running low. I'd rather face this thing in a house in Fort Lauderdale than in a car in a traffic jam somewhere outside Orlando.'

The Foreign Office has set up a hotline for people affected by the disaster and for people whose loved ones may be affected, on 020 7008 0000.