Greek authorities say 12 crew members of a Maltese-flagged cruise ship on a Greek island tour with more than 1500 people on board have tested positive to the 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 on Monday.

The first ship to dock in Greece after the COVID-19 lockdown, it had been due to sail to Piraeus, the country’s main port near the Greek capital, Athens, and later to the western island of Corfu.

Sample tests for the coronavirus were carried out on 150 of the crew, the ministry said, and 12 of them were found to be positive.

#MeinSchiff6 is currently on her first voyage with different stops in #Greece – incl a wonderful #shipmeeting with Mein Schiff 3 & Mein Schiff 5. 🇬🇷 It's one of the 1st cruise ships worldwide at this size to return to service including the offer of shore excursions. pic.twitter.com/0BQyQauLhc

— TUI Group (@TUIGroup) September 18, 2020

The passengers had undergone tests before boarding and were not part of the sample testing.

Those who tested positive had been isolated on board, and the cruise ship was headed to Piraeus.

The cruise firm tweeted on September 18 about its 10-point plan with highest #hygiene and #safety measures, and its newly created position of having an Infection Manager on board.

Greek health authorities said the ship was expected to arrive on Tuesday, and a National Public Health Organisation team would be on hand to re-test the 12 positive cases, as well as anyone else deemed necessary by the ship’s crew and on-board doctor.

The health authority said all 12 of those who had tested positive were asymptomatic and with a “low viral load”.