Former health minister Ko Wing-man on Sunday urged the government to find the right time to conduct a citywide mass-testing exercise, so as to completely clear local Covid-19 cases.

He said with Hong Kong seeing just a few hundred cases a day recently, it has to use the opportunity to get to zero.

"If we do not [get to zero], and on the other hand relax the social distancing measures, I think all of us have to be prepared for another kick up of the epidemic," Dr Ko told reporters after attending a Commercial Radio programme.

He noted that there are still transmission chains in the community and it remains unclear whether stronger and more transmissible mutant strains may appear.

Therefore, Hong Kong people need to keep their masks on, and Dr Ko said isolation facilities should be kept and not be converted into transitional housing.

He said Hong Kong, as part of China, cannot live with the virus like other places do, because doing so would cause a major blow to the country's health-care system, as it would find it hard to cope with the huge number of patients.

Dr Ko said a government review following the Sars outbreak in 2003 decided that for future epidemics in Hong Kong, the city should use stringent infection control measures to achieve early identification of patients, isolating them and conduct contact tracing.

That's similar to the country's zero-Covid policy nowadays, he said.