LONDON (AP) — London police say they will start using live facial recognition cameras in operational deployments, in a major advance for the controversial technology.

The Metropolitan Police Service said Friday it will use the cameras to automatically scan the faces of people passing through small targeted areas where intelligence suggests serious offenders will be found.

Real-time crowd surveillance by police in the British capital is among the more aggressive uses of facial recognition in modern democracies and raises questions about how the technology will enter people's daily lives. Rights groups said the London police deployment threatens civil liberties such as the right to privacy and represents an expansion of surveillance.

London police said the facial recognition system, which runs on technology from Japan's NEC, looks for faces in crowds to see if they match any on "watchlists" of people wanted for serious and violent offences, including gun and knife crimes and child sexual exploitation.