Around 100 "very serious" prisoners have escaped from jail on the British Virgin Islands in the wake of Hurricane Irma, a minister has said.
Foreign minister Sir Alan Duncan told the Commons that the convicts pose a "serious threat of the complete breakdown of law and order" on the overseas territory.
He told MPs: "The prison was breached, over 100 very serious prisoners escaped."
Sir Alan said Marines from RFA Mounts Bay were used to "protect the Governor and everything else about law and order" on Friday.
He said that more than 500,000 British nationals have been in the path of the hurricane and that 997 British military personnel are now in the Caribbean helping with the relief effort.
He added that while the death toll was low for a storm of this magnitude, the infrastructure on the island of Barbuda "no longer exists".
Foreign Secretary Boris Johnson is visiting the British territories devastated by the hurricane.
Sir Alan said: "Over 500,000 British nationals, either residents or tourists, have been in the path of Hurricane Irma, which has caused devastation across an area spanning well over 1,000 miles."
Giving an update to MPs, Sir Alan said five people had died in the British Virgin Islands and four in Anguilla.
Mr Johnson is expected to visit these British territories in the coming days.
In addition to the military personnel, 47 British police officers have also arrived in the British Virgin Islands to assist local officers.
Already, 20 tonnes of UK aid has arrived in the region, including more than 2,500 shelter kits and 2,300 solar lanterns.
Nine tonnes of food and water supplies are due to be flown out to Anguilla imminently, Sir Alan said.
He added that HMS Ocean, Britain's biggest warship in service, is heading to the Caribbean and should be there within 10 days.
There were 420,000 British citizens in Florida either as residents or visitors, where Hurricane Irma also caused devastation.
"We should all be humble in the face of the power of nature, and whatever relief we are able to provide will not be enough for many who have lost so much," said Sir Alan.
"But hundreds of dedicated British public servants are doing their utmost to help, and they will not relent in their efforts."
"And I'm pleased to say that 24 hours later, or 48 hours later, we've been able significantly to reinforce the Marines.
"So we have maintained and kept law and order on the British Virgin Islands, which at one point could have dramatically threatened the already-unfortunate plight of those who had been hit by the hurricane."
Shadow foreign secretary Emily Thornberry attacked the Government's response to the disaster for being "too little and too late".
She said it was "alarming" that almost a week had passed since the hurricane and Sir Alan was "still talking about the potential evacuation of British citizens".
"With the security situation deteriorating in many of the affected islands all British citizens should be considered vulnerable."
Ms Thornberry said the risk of waterborne infections was growing on some islands, and asked: "What is the Government doing as part of its emergency support for the overseas territories to help their governments establish command and control, maintain law and order where it is threatening to break down and put in place emergency plans to stop causes of preventable waterborne diseases before they begin to spread?"
She also urged the Government to create a "long-term plan" for the overseas territories to address threats posed by climate change.
"Can the minister confirm that when the Government sits down with their counterparts in the affected islands, the question of coping with climate change and future extreme weather events will be at the top of the agenda with financial commitments to match, not as usually happens, the afterthought which always proves too difficult and too expensive."
Priti Patel, Secretary of State for International Development, said the UK was working at "full throttle" to meet the "vast needs" of people hit by Hurricane Irma.
She said there were now 1,000 British soldiers and more than 50 police officers in the Caribbean helping to alleviate "tremendous hardship and suffering".
She added: "We're working on the ground to re-establish governance of those islands again."
The troops are delivering food and clean water alongside "survival packs", with the ship HMS Ocean heading over, loaded with thousands of "long term" supplies.
Questioned about lack of preparation, Ms Patel said some aid agencies who moved supplies on to islands before the storm ended up losing them.
She added that discussions around reconstruction had started and that "long term work and planning is in the pipeline".