Hong Kong announced a two-week ban on incoming flights from eight countries, including the United States and Britain, and tightened restrictions on Wednesday as authorities feared a fifth wave of Covid-19 infections.

The restrictions were announced as health authorities scoured the city for the contacts of a Covid-19 patient, some of whom had been aboard a Royal Caribbean ship that was ordered to cut short its "cruise to nowhere" and return to port.

Incoming flights from Australia, Canada, France, India, Pakistan, the Philippines, Britain and the United States, including interchanges, would be banned....