British overseas territories in the Caribbean are braced for Hurricane Maria which has become a “potentially catastrophic” category five storm.
The US National Hurricane Center has issued warnings to islands including Montserrat and the British Virgin Islands after recording 160mph winds.
UK International Development Secretary Priti Patel said ministers were under no illusion about the possible impact.
She said the government was taking steps to prepare communities.
The hurricane’s arrival in the Caribbean comes less than a fortnight after Hurricane Irma left a trail of destruction across the region, sparking a major UK relief effort to help communities in the British Virgin Islands and Anguilla.
The National Hurricane Center (NHC) said the centre of the storm was about 15 miles east south-east of Dominica and moving west north-west at about 9mph.
Hurricane Maria made landfall with Dominica on Monday and is expected to reach the British Virgin Islands on Tuesday night and into Wednesday.
The NHC said the British Virgin Islands were at risk of being hit by a dangerous storm surge with destructive waves raising the water level up to 9ft (2.7m).
Heavy rainfall could bring life-threatening flash flooding on the islands, it added.
Brig John Ridge, second-in-command of the UK military’s Joint Task Force, which has been distributing aid in the region following the devastation wreaked by Hurricane Irma, said the British Virgin Islands has “already been weakened” and that the situation “doesn’t look good”.
“It kind of does not matter which way the hurricane goes, it is bad,” he said. “They are either going to get the wind, which will pick up all the debris that is lying around.
“And also, irritatingly, where they have made progress in getting covers over the houses and power lines up, it will potentially damage that again.
“Or they get a huge amount of rain, which is also bad because of the blockages in the drainage channels; so the potential for some quite serious flooding as well.
“Whatever happens, it doesn’t look good, sadly.”
Ms Patel said British troops, police and aid experts were “working relentlessly” to help the victims of Hurricane Irma.
She added: “We are under no illusions about the possible impact of Hurricane Maria and are taking every measure possible to prepare communities which have already been devastated by Hurricane Irma.”
Hurricane Maria is predicted to deluge the Caribbean with up to 15ins (38cm) of rain, with “isolated maximum amounts of 20in (51cm)” expected in the British Virgin Islands.
The NHC warned that up to 8ins (20cm) could be recorded in Anguilla, and “could cause life-threatening flash floods and mudslides”.