“Our own failure, as well as the recent rise in infections internationally, has led us to halt all expedition cruises in Norwegian and international waters,” he said.

Norwegian police said they would investigate whether any laws had been broken.

“We have found grounds to open a case,” police lawyer Thomas Rye-Holmboe said.

Health authorities fear the ship also could have spread the virus to dozens of towns and villages along Norway’s western coast.

Four of the MS Roald Amundsen’s crew members were hospitalised on Friday when the ship arrived at the port of Tromso, north of the Arctic Circle, and later diagnosed with Covid-19. Tests showed another 32 of the 158 staff were also infected.

Among the infected crew, 32 were from the Philippines while the rest were of Norwegian, French and German nationality. The foreign crew had been tested for the coronavirus before leaving their home countries but did not quarantine before starting work on the ship, the company said.

Passengers were allowed to disembark before anyone had been diagnosed, triggering a complex operation to locate them.

So far, five of the combined 387 passengers travelling on the ship on two separate cruises since July 17 from Bergen to Svalbard, which is known for its polar bears, have been found to carry the virus, the Norwegian Institute of Public Health (FHI) and the Tromso municipality said.

Hurtigruten touted reduced passenger capacity, social distancing and strict rules on hygiene as it became the first operator to return an ocean-going cruise ship to service in mid-June.

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“It probably won’t be radical compared to what other companies have to do. I think the key is to be honest in how we operate, to reduce the risk for travellers.”

The MS Roald Amundsen had been expected to sail around the British Isles in September. Trips with two other vessels have also been suspended, the company said, adding its business shipping goods between Norwegian ports would continue.

But since the cruise line often acts like a local ferry, travelling from port to port along Norway’s western coast, the virus may not have been contained on-board. Some passengers disembarked along the route and may have spread the virus to their local communities.

A total of 69 municipalities in Norway could have been affected, Norwegian news agency NTB reported.

The city of Tromso is urging anyone who travelled on the ship or had any contact with it to get in touch with health authorities.

The Norwegian government announced on Monday it was tightening the rules for cruise ships by banning ships with more than 100 passengers from docking in Norwegian harbours and disembarking passengers and crew members.

The ban will be in place for two weeks and only applies to cruise ships, not ferry boats. Health Minister Bent Hoeie said the situation aboard the Hurtigruten ship served as “the background” for the decision.

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In Italy, the Costa Crociere cruise ship line said three crew members from two ships in Civitavecchia, near Rome, have tested positive for the coronavirus. The cruise company said two assigned to the Costa Deliziosa were hospitalised and a third, assigned to the Costa Favolosa, was in isolation on the ship.

In the South Pacific, some 340 passengers and crew are confined on a cruise ship in Tahiti after one traveller tested positive for the virus.

Cruise lines stopped sailing in mid-March after several high-profile coronavirus outbreaks at sea. More than 710 people fell ill aboard Carnival’s Diamond Princess cruise ship while it was quarantined off Japan and 13 people died.