Police on Tuesday said they plan to install up to 7,000 surveillance cameras across Hong Kong in roughly three years' time, up from the more than 600 put up since the start of this year.

The government had said the plan was to add 2,000 cameras each year from 2025.

At an Independent Police Complaints Council (IPCC) meeting, operations senior superintendent, Leung Ming-leung, said CCTV cameras are currently being put up on regular and smart lamp posts, government premises and transport interchanges.

Officers will look to put other cameras up on places like traffic lights, highway signboards and camera boxes to catch drivers running a red light.

The force said they are also looking into connecting cameras installed by other government departments to the police's CCTV system.

Leung said whether more cameras would be added beyond 2027 would depend on the situation at the time.

"There is a lot of time before 2027. It all depends on the actual situation, the number may be more, the number may be adjusted," he said.

"The speed with which we'll install the CCTV would hinge on the development of technology. Now the plan covers a horizon up to 2027, and closer to [that time], we are going to be having the latest thinking that we can bring members up to date on."

Leung said the force's CCTV cameras can record sound, but so far police have not used this function.

He said police will refer to overseas examples and operational needs going forward.

An IPCC member, Matthew Lam, asked whether Hong Kong would follow the example of Singapore in using facial recognition, for example at stadiums in the SAR where mega events take place.

In response, Leung said he thinks what Lam has in mind will come to fruition soon, saying the force will adopt technology that's proven successful elsewhere.

When asked what would happen if the police's system was hacked, Leung said the surveillance footage is encrypted and can only be viewed with special devices within the force.

He stressed the police attach great importance to privacy, saying when private places are filmed, the areas will be masked.

Footage in general will be kept for 31 days - unless it's useful in criminal cases.

Leung went on to say the installation of the cameras since the start of the year has been highly effective, saying 97 cases were resolved with their help, including serious crimes such as murder, arson and burglary.