A civil liberties group has described the technology as "authoritarian, dangerous and lawless"
Police have begun a facial recognition trial in central London that will be in effect on Monday and Tuesday of this week.
The trial will cover areas in the vicinity of Soho, Piccadilly Circus and Leicester Square, Met police said, with shoppers invited to take part rather than being filmed covertly.
However, privacy campaigners have described the technology as "authoritarian, dangerous and lawless", saying that the technology is inaccurate leading to innocent members of the public being added to police watch lists.
Silkie Carlo, director of Big Brother Watch, said: “The police’s use of this authoritarian surveillance tool in total absence of a legal or democratic basis is alarming.
"Live facial recognition is a form of mass surveillance that, if allowed to continue, will turn members of the public into walking ID cards.
Announcing the trial last week, police said that the technology would be used "overtly", adding that the technology will be carried out by a clear uniformed presence and information leaflets will be disseminated to the public.
"Anyone who declines to be scanned during the deployment will not be viewed as suspicious by police officers," the Met police said in a statement."
Carried out over two days in central London today's trial is part of a wider investigation into the technology by the force. It is hoped it can be used to cut down on violent crime.
The Met police's strategic lead for live facial technology, Ivan Balhatchet, said: “The Met is currently developing the use of live facial recognition technology and we have committed to ten trials during the coming months. We are now coming to the end of our trials when a full evaluation will be completed.
"We continue to engage with many different stakeholders, some who actively challenge our use of this technology. In order to show transparency and continue constructive debate, we have invited individuals and groups with varying views on our use of facial recognition technology to this deployment.”
