This comes as the government prepares to hand out rapid at-home test kits to every household from Saturday.
Chief Executive Carrie Lam had said the RAT tests will be used to gauge the level of infection in the community.
But Chan told a Legco panel meeting on Friday that the self-administered tests will complement, rather than replace, the more accurate PCR tests.
“We have been treating nucleic acid tests as the ‘gold standard’ for compulsory testing notices,” she said.
“Of course we are using many rapid antigen test kits, because there are a lot of transmission chains in the community. If we want to track them down quickly, we use both tests.”