ATHENS — Greek authorities say 12 crew members on a Maltese-flagged cruise ship carrying more than 1,500 people on a Greek islands tour have tested positive for coronavirus and have been isolated on board.

The Mein Schiff 6, operated by TUI Cruises, began its trip in Heraklion on the southern Greek island of Crete on Sunday night, with 922 passengers and 666 crew members on board, Greece’s Shipping Ministry said Monday. It had been due to sail to Piraeus, the country’s main port near the Greek capital of Athens, and later to the western island of Corfu.

Sample tests for coronavirus were carried out on 150 crewmembers and 12 were positive but asymptomatic, the ministry said. The passengers had undergone coronavirus tests before boarding.

Greek health authorities said the ship would arrive at Piraeus on Tuesday and a National Public Health Organization team will re-test the 12 positive cases, as well as anyone else deemed necessary by the ship's crew and doctor.

Greece on Monday recorded 269 new confirmed infections, most of them in the greater Athens region, and four coronavirus-related deaths. That brings the total cases in the country of 10 million to about 17,700, and the overall death toll to 383.