Royal Caribbean Cruises Ltd said on Friday it would ban guests holding China, Hong Kong or Macau passports from boarding its ships amid concerns over the coronavirus outbreak.

The company's new protocols come in the wake of the fast-spreading virus, which has killed more than 600 people and has affected over 31,000 individuals in at least 25 countries.

Guests or crew members who have traveled to, from or through mainland China, Hong Kong or Macau, or been in contact with someone who has, less than 15 days before sailing will not be allowed to board the company's ships under the new rules.

The company would also screen guests with flu-like symptoms and those who are unsure if they had been in contact with individuals who had visited China or Hong Kong in the past 15 days.

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Royal Caribbean on Friday also delayed the departure of its Anthem of the Seas cruise from New Jersey by a day after four guests were tested by the US Centers for Disease Control and Prevention (CDC) for coronavirus.

None of the four showed any clinical symptoms of the virus, the company said.

The CDC had screened 27 passengers on the ship who had recently traveled from China.