Medical sector lawmaker David Lam on Tuesday welcomed news of an upcoming resumption of quarantine-free travel to the mainland and the expected return of cross-border visitors, but warned that Hong Kong should keep on isolating people with Covid and imposing tests on arrivals from abroad.

Beijing says people arriving in China will no longer have to quarantine from January 8, though it is not yet clear whether the Hong Kong-mainland border will fully reopen on this date.

"Since we've been waiting for [the reopening] for so long, and that the new strains of Omicron come with a relatively low mortality rate, we can safely and steadily reopen with mainland China," Lam told RTHK, adding that the majority of local residents are triple-jabbed against the virus.

But he also cautioned that despite the mainland's relaxation of rules, Hong Kong should keep its PCR tests at the border for international arrivals, as well as isolation for anyone in the territory who tests positive.

Lam noted that it is difficult for people to get PCR tests abroad and said those given to arrivals in Hong Kong would likely be the only ones they get before entering the local community.

"If we do not test them at the border, that means no test, which is a bit hazardous," the legislator told RTHK.

"If we do away with the tests altogether, then we're really opening the borders too widely."

However, Lam said people coming from the mainland should be exempt from a PCR test in Hong Kong and allowing them to take one across the border within 48 hours of their trip is sufficient.

The legislator also said the authorities must ensure that the local healthcare system isn't overwhelmed with Covid patients.

Contingency plans should be put in place, such as using vacant quarantine centres to look after patients who aren't seriously ill, he said.