At least 48 crew aboard a cruise ship docked in the Japanese city of Nagasaki have tested positive for coronavirus, local authorities said Thursday after confirming 14 additional cases.

The Costa Atlantica first arrived in Nagasaki in January to undergo repairs, with around 600 crew on board.

Officials said they hoped to test all crew members by the end of the week with "some 200 to 300" tests likely to be conducted on Thursday.

Over the weekend, the ship's operator contacted local authorities seeking help to test suspected cases on board.

An initial four tests carried out on the ship revealed a first infection on Monday, with additional testing among 57 crew finding a total of 34 cases by Wednesday.

On Thursday, 66 new test results revealed the 14 additional infections, Nagasaki official Katsumi Nakata told reporters.

At least 48 crew aboard the Costa Atlantica cruise ship docked at a port in Nagasakia have tested positive for coronavirus
A cruise ship is pictured. JIJI PRESS / STR

Those 14 people are self-isolating in their cabins, Nakata said.

At least one crew member has been sent to hospital and requires a ventilator, the official said.

Japan has already dealt with one virus outbreak on a cruise ship -- the Diamond Princess, which docked in Yokohama after a former passenger tested positive for the disease.

Authorities ordered an on-ship quarantine, but more than 700 people ultimately contracted the virus, and 13 died.

Overall, Japan has seen a relatively small outbreak compared to parts of Europe or the United States, with nearly 12,000 infections and around 290 deaths recorded so far.

But a recent jump in infections has caused concern, put pressure on local healthcare facilities and prompted the government to declare a month-long state of emergency that will run until May 6.