A High Court judge has put on hold the invalidation by the government of some 20,000 Covid-19 vaccination exemption certificates issued by seven private doctors, pending a legal challenge.

Justice Russell Coleman on Tuesday issued an interim relief order to that effect until a judicial review hearing next week.

The application for the legal challenge was filed by Kwok Cheuk-kin, the so-called "king of judicial reviews", who said the government should not nullify the exemption certificates before they are found to have been issued improperly by the doctors.

At a case management hearing at the High Court, government lawyers representing Secretary for Health Lo Chung-mau said he had ordered that the certificates be invalidated to protect public health, as it would effectively ban their holders from entering restaurants and other premises.

They also said those affected by the move could consult another doctor to obtain a new exemption certificate, and could even see a government doctor for free.

The certificates were supposed to be invalidated from Wednesday.

Justice Coleman said he made the decision mainly because the judicial review hearing would take place imminently, on Thursday next week.

Kwok welcomed the judge's decision. "Hong Kong is a society [governed by] the rule of law... If the seven [doctors] were found not guilty by the court, and the vaccination exemption certificates were invalidated, who can compensate [those affected]?" he told reporters outside court.