The Health Secretary, Sophia Chan, said the government is still considering whether to impose a lockdown when it tests everyone in the SAR for Covid-19 next month.
Officials had said all seven million residents will be tested three times over March in an effort to contain the latest Covid outbreak
Chief Executive Carrie Lam had, on a number of previous occasions, rejected the idea of a "complete, wholesale lockdown" to go with the mass-testing.
But appearing on a Commercial Radio programme on Monday, Chan said this option has not been ruled out.
"We are still discussing the matter. From the public health perspective, we should maximise the effectiveness of the universal testing programme," she said.
"To achieve this, we need to reduce the flow of people. People should not go out.. or they should stay home as far as possible."
Chan added that some or even all of the specimens collected during the exercise could be sent to the mainland for testing as Hong Kong doesn't have the capacity to handle them.
The health chief's remarks came after a senior official from the National Health Commission, Li Dachuan, said Hong Kong's universal testing programme would achieve a better result if it is complemented by a lockdown.
Li added that a team of 9,000 testing staff has been formed on the mainland, ready to come to Hong Kong to collect specimens during the testing programme.