The US cruise ship company Royal Caribbean has announced that would-be passengers and crew with Chinese passports will be banned from all of its cruise ships – regardless of when they were last in the country at the centre of the coronavirus outbreak.

The measure – which also covers people with Hong Kong and Macau passports – comes amid growing concerns over the fast-spreading virus, which has killed more than 700 people and affected individuals in at least 25 countries.

But it was likely to face criticism from Beijing, which has bridled at sweeping travel bans on its citizens, and from human rights activists who have denounced such restrictions as discriminatory.

Friday’s announcement by the Miami-based company came after four travelers who were onboard the company’s Anthem of the Seas cruise ship were hospitalized in New Jersey after experiencing feverish symptoms. According to Royal Caribbean, the passengers had come from China for the cruise from the port of Bayonne, New Jersey, to the Bahamas, and were hospitalized out of caution.

“None of the four guests being tested by [the Centers for Disease Control and Prevention] showed any clinical signs or symptoms of coronavirus,” Royal Caribbean said in a statement. “We will delay our [next] departure until tomorrow.”

They added, however, that one guest did test positive for influenza A. The CDC reports no one in New Jersey has been found with the virus so far.

The four are among more than two dozen Chinese nationals who were screened for signs of the new virus onboard the cruise ship. None of them were reportedly from Wuhan, the city at the center of the outbreak.

Earlier this week, after the US government announced it would quarantine US citizens returning from certain parts of mainland China, the American Civil Liberties Union responded by saying the measures “fly in the face of considerable evidence that travel bans and quarantines can do more harm than good”.

“The more dangerous the actual outbreak, the more critical it becomes that we respond in ways that are grounded in science,” analyst Jay Stanley said in a statement at the time.

The ACLU has not yet responded to requests for comment on Royal Caribbean’s specific ban.

Royal Caribbean instituted other new boarding restrictions and passenger screenings in response to the virus, including mandatory screenings performed for guests unsure about their recent contact with others, or those who experience flu-like symptoms.

It added that “any guest or crew-member traveling from, to, or through mainland China, Hong Kong, or Macau” less than two weeks “prior to their sailing will be unable to board any of [their] ships”, regardless of nationality.

“We take this very seriously and have a responsibility to maintain a safe and healthy environment onboard our ships, as well as in the ports we visit,” the statement read.

Royal Caribbean acknowledged potential backlash in their statement.

“In alignment with new stricter CDC protocols, we are tightening our measures to protect guests and crew. These steps are intentionally conservative, and we apologize that they will inconvenience some of our guests,” the cruise line said in a statement.

The ship departs again on Saturday and announced passengers would be compensated with an onboard credit for the day lost.