Police Commissioner Raymond Siu on Saturday said security cameras, installed in Mong Kok this month, have helped officers detect two serious crimes. Their installation was the first stage of a government plan to install about 2,000 CCTV cameras across Hong Kong this year.

Speaking to reporters after attending an event, Siu said the surveillance cameras had been effective.

"In just half a month, we detected two serious crime cases with the help of CCTV cameras. One was related to possessing imitation firearms, and we arrested three men. The other one was a robbery case, and we arrested a man within 24 hours," he said.

"After installing these 15 CCTV cameras, we will see if there’s anything we can improve. We will then install 600 cameras at crime black spots across Hong Kong in the middle of this year."

Asked about privacy concerns, Siu said the Privacy Commissioner had given advice to the government, and that the authorities had also asked an independent consultancy firm to conduct a privacy impact assessment.