The administration says the measure is needed to enhance contact tracing. Exemptions will apply only to those aged under 12 or over 65, as well as disabled people.
During an RTHK programmme, a caller asked Chu if the measure would amount to discrimination against others who could not use the app.
Chu said people who don’t have smartphones should not be treated differently.
He hoped the problem could be solved via administrative procedures when the requirement takes effect next month.
“It’s not discrimination within the prevailing legal regime. It’s unfair because the cause of the problem is involuntary… not something that the marginalised group can cope with because of limitation in resources,” he said.
“How to resolve this problem… we can treat it from a procedural point of view. I think the spirit could be offering some alternatives. How to implement such alternatives… I think the government would definitely need to consider.”
Speaking on another radio programme, Health Secretary Sophia Chan said different government departments were studying the details of how the requirement should be implemented.