The UN says around 70,000 people in the Bahamas are in need of urgent aid following Hurricane Dorian.
Grand Bahamas and Abaco experienced a direct hit from the powerful storm in recent days, causing "unprecedented" levels of destruction.
Officials say at least 20 people were killed during the hurricane, with search and rescue operations ongoing on the islands.
However, access to the impacted areas remains "very limited" due to the scale of the damage.
UN relief chief Mark Lowcock travelled to the Bahamas yesterday amid efforts to expedite the aid efforts.
Mr Lowcock said there was "vast devastation" on the islands.
He explained: “It’s very unusual, for 20% of the population of a country to be very severely impacted by a single event like this…
"The Bahamas has certainly never seen anything on the scale.
“If you imagine in other places what it would be for 20% of the population of the country to have their lives turned upside down and their homes devastated... just imagine something of that order and you get a sense of what the scale of the challenge facing the Bahamas is now."
UN Secretary-General Antonio Gutteres, meanwhile, said he remains "deeply concerned" about the situation:
I’m deeply saddened by the lives lost and terrible destruction caused by #HurricaneDorian in the Bahamas.
People who have lost everything are in desperate need of shelter, safe drinking water and food. The UN will continue to support relief and recovery efforts.
— António Guterres (@antonioguterres) September 5, 2019
Hurricane Dorian - which has been downgraded to category 3 but remains powerful - is currently moving off the east coast of the US with sustained winds of up to 185km/h.
High winds and heavy rain are being reported in Georgia and the Carolinas, with warnings of potential flash flooding.
The US National Hurricane Centre also says "life-threatening storm surge and dangerous winds" are expected.