ATHENS - A cruise ship carrying about 920 passengers docked at Piraeus port near Athens early on Tuesday and a repeat test for 12 of its crew members was negative for the coronavirus, a Greek health ministry official said.

The Mein Shiff 6, operated by TUI Cruises, departed from Heraklion in Crete on Sunday with all passengers having tested negative before boarding.

But sample tests on 150 crew members out of a total of 666, detected 12 infections, and the ship had to return to Piraeus, the country's biggest port, with better access to health services and equipped to deal with any emergency.

TUI Cruises said late on Monday that a second round of tests held on board showed that half of the crew found positive earlier had since tested negative.

On Tuesday morning, a health ministry official said that repeat tests for the rest of the 12 crew members conducted en route to Piraeus were also negative.

Greek health authorities boarded the ship on Tuesday morning and conducted a third test, the official said, adding that results were expected later in the day.

TUI Cruises has said that the affected crew on the ship, which made its way back to Piraeus from off the island of Milos, have been isolated, adding that all crew members would be tested.

The cruise industry has taken a major hit from the pandemic, with some of the earliest large clusters of COVID-19 occurring aboard cruise ships.

Voyages of large cruise ships only resumed in recent weeks in Greece after they were banned for months.

TUI Cruises is a cruise line based in Germany.