WASHINGTON (AFP) - The captain of the US nuclear-powered aircraft carrier Theodore Roosevelt told the Pentagon that the coronavirus is spreading uncontrollably through his ship and called for immediate help to quarantine its huge crew.

Captain Brett Crozier wrote in a four-page letter that they had not been able to stem the spread of the Covid-19 virus through the 4,000 crewmembers, describing a dire situation aboard the vessel now docked at Guam.

"We are not at war. Sailors do not need to die," Crozier wrote, according to the San Francisco Chronicle, which published a copy of the letter on Tuesday (March 31).

"The spread of the disease is ongoing and accelerating," Crozier wrote, referring to the ship's "inherent limitations of space."

He asked to be able to quarantine nearly the entire crew onshore at Guam, saying keeping them all on board the ship was an "unnecessary risk."

"Removing the majority of personnel from a deployed US nuclear aircraft carrier and isolating them for two weeks may seem like an extraordinary measure," he said.

"This is a necessary risk."

OVER 100 CASES ON BOARD

The Chronicle said that more than 100 aboard the warship had been confirmed infected with Covid-19, around four times the figures being given last Friday.

Crozier asked in the letter for quarantine facilities for the entire crew on Guam.

"If we do not act now, we are failing to properly take care of our most trusted asset - our sailors," he wrote.

The US Navy did not confirm the contents of the letter, which were also reported by The New York Times.

In a statement, a Navy official under condition of anonymity said that Crozier had alerted his Pacific fleet leaders on Sunday of the problems aboard the warship.

"The ship's commanding officer advocated for housing more members of the crew in facilities that allow for better isolation," the officials said.

"Navy leadership is moving quickly to take all necessary measures to ensure the health and safety of the crew of USS Theodore Roosevelt, and is pursuing options to address the concerns raised by the commanding officer."

VIETNAM PORT STOP

Some speculated that the infection could have begun with a port stop in Vietnam by the Roosevelt.

The carrier put in to Da Nang port for five days in early March, when the virus was raging in China and more than a dozen cases had been detected in Vietnam.

Acting Navy Secretary Thomas Modly told CNN Tuesday that he agreed with Crozier on the seriousness of the situation, and that they had been working over the past few days to move people off of the Roosevelt.

However, he said, facilities to sequester the afflicted sailors in Guam, which hosts a major US naval base, are limited.

"The problem is that Guam does not have enough beds right now. We are having to talk to the government there to see if we can get some hotel space, create some tent-type facilities there," Modly said.

Modly acknowledged having the aircraft carrier tied up in port was a challenge to military readiness.

"We have the responsibility to protect the seas and to protect our friends and allies around the world. We have to adjust of the best way we can to do that," he said.