Hong Kong,  Hong Kong will impose a China-style Covid-19 app on the city's seven million residents, sparking fears of ever-increasing state control over the movement of individuals, media reports said.

The city will start putting electronic bracelets on those who test positive for the virus from July 15, Health Secretary Lo Chung-mau said during a press briefing, RFA reported.

In China, red codes banning movement in public places have already been used to target people for political reasons that have little to do with their health, the report said.

Hong Kong Chief Executive John Lee said the city needed to "be realistic" about the kind of risks it could be facing, citing average daily infections of around 3,000 with rapidly rising hospitalisation rate.

"That is why we are thinking of designing methods that will be able to allow us to react more quickly, to respond more precisely, and at the same time, allow more people to be not so restrictive in their activities," Lee told journalists.

Health Secretary Lo said the LeaveHomeSafe app would be updated soon, and would require people to register using a ID verified form.

Lo said a person's health code would turn red, preventing them from going to public places, on confirmation of a Covid positive result, while new arrivals to the city would be given an amber code, restricting them entry to certain high-risk places.

A Hong Kong resident surnamed Mak said the app will function as a tool for those in power to monitor and control citizens.

"It divides people into different categories, and people with a red code are denied the right to use any facilities or services, including withdrawing money from the bank," Mak said, RFA reported.