Hong Kong's health officials said on Friday the Omicron variant of the coronavirus has made its way past some of the world's toughest Covid-19 restrictions, with the city reporting its first cases outside its strict quarantine system.

The findings raise risks that the global financial hub might keep its borders shut well into 2022. It has largely isolated itself from the world hoping in turn to open the border with mainland China for a limited number of business travellers.

Hong Kong's last Covid-19 case...