Officials in Puerto Rico now say 2,975 people died following Hurricane Maria – a devastating storm that struck the US island territory in September 2017.
The revised death toll is nearly 50 times the previous estimate of 64.
Governor Ricardo Rossello “accepted” the findings in a long-awaited independent investigation.
Puerto Rico has struggled to repair its infrastructure and power grid since the storm, and is asking US Congress for $139bn (£108bn) in recovery funds.
“I’m giving an order to update the official number of deaths to 2,975,” Governor Ricardo Rossello said at a press conference on Tuesday. “Although this is an estimate, it has a scientific basis.”
In a statement, the White House said the federal government supported the governor’s efforts to “ensure a full accountability and transparency of fatalities” in last year’s hurricane.
President Donald Trump was criticised for praising the federal response to the hurricane-ravaged island in the weeks following the storm. Critics accused him of showing more concern for residents in Texas and Florida after they were hit by hurricanes.
Why the change in numbers?
The authorities have faced nearly a year of criticism for underreporting the true toll of Maria – the most powerful storm to hit the region in nearly 90 years.
Until now, the official figure was 64 – even though the island had previously acknowledged the death toll was probably much higher. In the wake of the disaster, some experts estimated as many as 4,600 deaths.
The government’s initial number was arrived at by counting those crushed by collapsing structures, drowned and hit by flying debris.
The latest findings – accepted by the island’s authorities – were made in a report by experts from George Washington University, which the governor commissioned.
“This shows the magnitude of the catastrophe,” Governor Rossello told newspaper El Nuevo Dia.
When asked why his government was unable to recognise a higher death toll, he replied: “I am not perfect. I make mistakes. Now, hindsight tends to be 20-20.”
He echoed one finding in the report – that doctors “lacked awareness” on how to appropriately certify deaths attributed to natural disasters.
Media captionMonths after Maria, many on this US island still suffered in the dark
“The responsibility for adjudicating the cause of deaths rested with the doctors,” Mr Rossello told the island’s most circulated paper. “But unfortunately there was no formal process to prepare them for this kind of devastation.
“At that moment, that was the number [of deceased] that we had and today we have the evidence which indicates the number was definitely higher.”
What does the report say?
Researchers tracked the number of deaths using death certificates and other mortality data between mid-September 2017 to mid-February of this year.
Many people died as a result of poor healthcare provision and a lack of electricity and clean water. Repeated power outages also led to an increased number of deaths from diabetes and sepsis.
The Caribbean island is home to 3.3 million US citizens, some 8% of which have since left the island, the study said.
It also said that those from poorer backgrounds in Puerto Rico were 45% more likely to have been killed in the aftermath of the hurricane.
The governor said he would sign an executive order to create a committee to examine and put into practice the report’s recommendations.
Is this controversial?
Puerto Rico has been reeling ever since this devastating storm hit its shores – with residents still suffering blackouts, broken infrastructure and a lack of services.
Hurricane Maria caused the largest blackout in US history, according to research consultancy the Rhodium Group.
It is ranked as the third most financially costly cyclone in US history since 1900, yet its death toll is a third higher than the costliest – Hurricane Katrina in 2005, with an estimated 1,833.
The new study raises questions about US President Donald Trump’s response to the disaster.
During a visit in October, Mr Trump had suggested officials should be “proud” the death toll – at the time only 16 – was not as high as “a real catastrophe” like Katrina.
Official recognition moves recovery forward
Gary O’Donoghue, BBC Washington correspondent
For close to a year, Puerto Rico’s government has clung to the idea that 64 people died as a result of Maria.
That figure was always risible – particularly when you consider that the 150 mph (241 kmh) winds caused around $90bn worth of damage and left households for, on average, 84 days without electricity; 64 days without water and 41 days without cellular telephone coverage.
But now the governor, Ricardo Rossello, has bowed to the inevitable and ordered the official toll to be updated more than forty-fold.
In truth, the new official number is still an estimate – based on mortality data and taking into account historical data on migration patterns.
But the official recognition will allow the island to move on and focus fully on rebuilding its infrastructure and extracting the tens of billions of dollars needed from Congress to give the three million inhabitants of this already bankrupt territory something of a future.