HONG KONG -- Hong Kong's Center for Health Protection reported on Saturday 18 new cases of COVID-19, with the number of untraceable ones the highest in almost five weeks.

Of the new cases, 10 were imported and eight were locally transmitted, including six untraceable infections, according to a CHP press conference. There were also over 20 preliminary cases.

The CHP warned of the resurgence of cases with an unknown origin, among which a variant of COVID-19 was found.

CHP controller Ronald Lam said the most stringent measures have been taken to prevent the spread of the new strain and called on the public to remain alert and get vaccinated as soon as possible.

Hong Kong's COVID-19 tally stood at 11,653. Some 345,900 people have been fully vaccinated under a government inoculation program.