* U.S. Navy ship docks on Manhattan's West Side

* Field hospital going up in city's Central Park (Updates with mayor's comments, arrival of Navy ship)

By Stephanie Kelly and Daniel Trotta

NEW YORK, March 30 (Reuters) - New York City Mayor Bill de Blasio on Monday pleaded with the Trump administration for more medical supplies to battle the coronavirus, saying the death toll in the city, a key epicenter of the outbreak, would rise if help did not arrive by Sunday.

With infections and deaths mounting across the country and the economy at a virtual standstill, de Blasio joined a growing chorus of officials in expressing frustration at Washington's handling of the crisis.

De Blasio spoke as a 1,000-bed U.S. Navy hospital ship arrived in New York Harbor and docked on Manhattan's west side after departing Norfolk, Virginia. The USNS Comfort will treat non-coronavirus patients, including those who require surgery and critical care, the Navy said in a news release.

"If we don't get more consistent federal help in a growing crisis, there's a danger we start to lose lives that could have been saved," the New York City mayor said in an interview with CNN. "Sunday is D-Day, we need help by Sunday."

Hospitals in New York have been overrun with patients suffering from COVID-19, the respiratory illness caused by the virus. New York state accounts for almost half of the country's 141,883 cases and more than a third of its 2,477 deaths, according to a Reuters tally. The United States has the most cases in the world.(Graphic: https://tmsnrt.rs/2w7hX9T)

Construction of a 68-bed field hospital began on Sunday in New York's Central Park, and the new site was expected to begin accepting patients on Tuesday, de Blasio said separately in a statement.

The makeshift facility, provided by Mount Sinai Health Systems and non-profit organization Samaritan's Purse, will not take walk-ins, and admissions and transfers will be managed by Mount Sinai, de Blasio said.

More than 1,100 Navy medical personnel and support staff were on board the Comfort.

In Los Angeles, another Navy hospital ship, the USNS Mercy, began accepting patients on Sunday, also to treat noncoronavirus patients. With infections and deaths mounting across the country and the economy at a virtual standstill, de Blasio joined a growing chorus of officials in expressing frustration at Washington's handling of the crisis. In New Orleans, another outbreak epicenter, authorities were setting up a field hospital at the Ernest N. Morial Convention Center - the same site where thousands of Hurricane Katrina refugees suffered in 2005 - to handle the expected overflow of patients.

CHILLING NUMBERS

In Washington, health officials urged Americans to follow stay-at-home orders and other measures to contain the spread of the virus, which originated in China and has infected about three-quarters of a million people around the world.

"If we do things together well - almost perfectly - we could get in the range of 100,000 to 200,000 fatalities," Dr. Deborah Birx, coordinator of the White House's coronavirus task force, told NBC's "Today" show.

Dr. Anthony Fauci, a top U.S. health official, cited those figures on Sunday as a possible outcome, but Birx's assessment appeared to suggest the figures could be a floor rather than a ceiling.

The New York Times reported earlier this month that models from the U.S. Centers for Disease Control and Prevention projected that 200,000 to 1.7 million people could die and between 160 million and 214 million people could be infected.

The Times based its report on less specific models, translating CDC percentages into absolute numbers after consulting with independent experts. U.S. officials played down those models at the time.

"We allowed the seeds to be planted. And now there is nothing to do but wait for the bloom. A lot of these deaths are already percolating," said Dana Miller, 61, of Belmont, Massachusetts, a retired health policy official in the U.S. government.

President Donald Trump, who initially played down the risk of the outbreak to Americans, said his administration was seeking to secure hazard pay for healthcare providers in direct contact with the virus.

"We are looking at that and we are looking at that either as an amendment or something," Trump, who is up for re-election in November, told Fox News a day after he abandoned a hotly criticized plan to get the economy up and running by mid-April.

Trump on Friday signed a $2 trillion package of emergency measures that authorizes direct payments to households, loans to small and large companies, and funding that the Federal Reserve may leverage into as much as $4 trillion more in credit.

He also has extended his original 15-day nationwide stay-at-home order for another 30 days, a step that many Americans accepted with resignation.

"I'm sad to be locked inside, but I think it's for the best," said Mia Siracusa, 24, a data manager ordered to work out of her apartment in Brooklyn, whose live-in boyfriend is from Italy and whose mother is a New York City hospital nurse.

"I get frustrated when people don't stay in," she said. "I am frustrated that our federal government didn't get a handle on this sooner."

Fauci, director of the National Institute of Allergy and Infectious Diseases, told CNN on Monday that White House health experts had argued strongly with Trump for the extension.

"We felt that if we prematurely pulled back, we would only form an acceleration, or a rebound of something, which would have put you behind where you were before," Fauci said.

(Reporting by Dan Trotta, Maria Caspani, Barbara Goldberg and Stephanie Kelly in New York and Doina Chiacu and Lisa Lambert in Washington; Writing by Paul Simao Editing by Howard Goller)

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