The Republican president said Democrats inflated the number of dead from two hurricanes that hit Puerto Rico last year in order to make him look "as bad as possible."
US President Donald Trump on Thursday disputed Puerto Rico's official death toll of 3,000 from hurricanes last year and accused Democrats of inflating the figure reached in an independent academic study.
Trump bristled at criticism of his administration's handling of the Puerto Rico disaster as Hurricane Florence approached the coast of North Carolina and began to unleash fierce rains that forecasters warned would cause catastrophic flooding across a wide swath of the US southeast.
The Republican president said Democrats inflated the number of dead in Puerto Rico "in order to make me look as bad as possible" but he did not provide evidence.
Some well-known Republicans split with Trump on the issue. Privately, some White House officials were exasperated with the president's focus on Puerto Rico at a time when Florence is bearing down on the US East Coast.
In a tweet, Trump said: "3000 people did not die in the two hurricanes that hit Puerto Rico. When I left the Island, AFTER the storm had hit, they had anywhere from 6 to 18 deaths. As time went by it did not go up by much. Then, a long time later, they started to report really large numbers, like 3000."
3000 people did not die in the two hurricanes that hit Puerto Rico. When I left the Island, AFTER the storm had hit, they had anywhere from 6 to 18 deaths. As time went by it did not go up by much. Then, a long time later, they started to report really large numbers, like 3000...— Donald J. Trump (@realDonaldTrump) September 13, 2018
Puerto Rico was recovering from Hurricane Irma before Hurricane Maria hit in September 2017, destroying roads and bridges and leaving much of the Caribbean island without electricity for months.
The death toll from Maria, the most powerful storm to hit there in almost a century, was raised last month from 64, a number widely discounted as far too low, to 2,975.
That number was produced by public health experts at George Washington University in Washington in a report commissioned by the US territory's governor, Ricardo Rossello.
The study found that those deaths could be attributed directly or indirectly to Maria from the time it struck in September 2017 to mid-February of this year.
The report compared predicted mortality under normal circumstances and deaths documented after Maria.
Rossello said Puerto Ricans "do not deserve to have their pain questioned" and backed the study.
"We left this analysis to the scientists and experts, recognising that there would be many challenges, because we wanted to have a powerful and independent voice to minimise the uncertainty," he said in a video on Facebook.
George Washington University stood by its estimate. "We are confident that the number - 2,975 - is the most accurate and unbiased estimate of excess mortality to date," the school said in a statement.
At the same time, the top Republican in Congress, House of Representatives Speaker Paul Ryan, said he had no reason to dispute the official death toll, while Republican Senator Marco Rubio said tragedy should not be politicised.
"I disagree with @POTUS," Florida Governor Rick Scott, a Republican, said on Twitter.
I disagree with @POTUS– an independent study said thousands were lost and Gov. Rosselló agreed. I've been to Puerto Rico 7 times & saw devastation firsthand. The loss of any life is tragic; the extent of lives lost as a result of Maria is heart wrenching. I'll continue to help PR— Rick Scott (@ScottforFlorida) September 13, 2018
The emergency response to Maria became highly politicised as the Trump administration was criticised as being slow to recognise the extent of the devastation and too sluggish in providing disaster relief to Puerto Rico, an island of more than 3 million residents.
Trump touted the federal government's response as "an incredible, unsung success" this week.
Thursday's tweets drew the ire of Carmen Yulin Cruz, the mayor of Puerto Rico's capital, San Juan, who has sharply criticised both the president and his administration's response to Maria.
"This is what denial following neglect looks like: Mr Pres in the real world people died on your watch. YOUR LACK OF RESPECT IS APPALLING!" she wrote on Twitter before calling Trump delusional and unhinged from reality.
On Wednesday, Puerto Rican officials said about 20,000 pallets of water bottles shipped to Puerto Rico after Maria went unused and became too contaminated to drink.
This is what denial following neglect looks like: Mr Pres in the real world people died on your watch. YOUR LACK OF RESPECT IS APPALLING! pic.twitter.com/OJEDqT74Sr— Carmen Yulín Cruz (@CarmenYulinCruz) September 13, 2018