An ocean liner on a "cruise to nowhere" was forced to make an earlier-than-scheduled return to Singapore Wednesday after a coronavirus case was detected on board, authorities said.

The Dream Cruises ship's 1,646 passengers and 1,249 crew members have been asked to remain in their cabins as the vessel is disinfected and contact tracing completed, the Singapore Tourism Board's director for cruises said.

"The passenger was identified as a close contact of a confirmed case on land, and was immediately isolated as part of onboard health protocols," said Annie Chang.

A 'cruise to nowhere' was cut short in Singapore on Wednesday after a coronavirus case was detected on board
A 'cruise to nowhere' was cut short in Singapore on Wednesday after a coronavirus case was detected on board AFP / Roslan Rahman

The 40-year-old passenger, who had tested negative before boarding, was taken to hospital for further tests, and the health ministry later confirmed the passenger had the virus.

Local media reported the guest was fully vaccinated.

Chang said that as part of onboard health protocols, the passenger's three travelling companions were identified and isolated. All have tested negative for the virus.

Passengers on board were told early Wednesday that a positive Covid case had been detected on the ship
Passengers on board were told early Wednesday that a positive Covid case had been detected on the ship AFP / Roslan Rahman

The cruises -- starting and ending in Singapore, with no stops -- were launched last year as part of the travel industry's attempt to bounce back from a pandemic-induced crunch.

They have proved popular among those seeking an escape from the tiny city-state, which has only had a mild outbreak but largely kept its borders closed.

The ship, owned and operated by Malaysian conglomerate Genting Group, left Singapore on Sunday evening for the four-day cruise and returned to port several hours earlier than scheduled.

Genting's Dream Cruises said it cancelled a voyage scheduled to depart later Wednesday, and that there had been no virus infections on any of its previous cruises.

A Royal Caribbean "cruise to nowhere" was also cut short in December after an elderly man tested positive. However, that case proved to be a false alarm, with subsequent results coming back negative.

The cruise industry worldwide is struggling to get back on its feet after voyages were halted at the start of the pandemic, and several vessels were hit by outbreaks.