A civil liberties group heading to the Court of Appeal to challenge police deployment of automated facial recognition technology has condemned a London police force's decision to deploy the technology.

The Metropolitan Police announced today that it will deploy live facial recognition technology 'at locations where intelligence suggests we are most likely to locate serious offenders'. Each deployment will have a bespoke 'watch list', comprising images of wanted individuals, and predominantly those wanted for serious and violent offences.

The London force said that, at deployment, cameras will be focused on a small, targeted area to scan passers-by. The cameras will be signposted and officers deployed to the operation will hand out leaflets about the activity. The technology, a standalone system, will not be linked to any other imaging system, such as CCTV, body-worn video or ANPR.

Assistant commissioner Nick Ephgrave said: 'We are using a tried-and-tested technology, and have taken a considered and transparent approach in order to arrive at this point. Similar technology is already widely used across the UK, in the private sector. Ours has been trialled by our technology teams for use in an operational policing environment.

'Every day, our police officers are briefed about suspects they should look out for; LFR improves the effectiveness of this tactic. Similarly, if it can help locate missing children or vulnerable adults swiftly, and keep them from harm and exploitation, then we have a duty to deploy the technology to do this.'

Liberty, which is challenging South Wales Police's use of the technology, said today's announcement was a 'sinister step', pushing the UK into a 'surveillance state'.

Clare Collier, Liberty advocacy director, said: 'This is a dangerous, oppressive and completely unjustified move by the Met. Facial recognition technology gives the state unprecedented power to track and monitor any one of us, destroying our privacy and our free expression. Rolling out an oppressive mass surveillance tool that has been rejected by democracies and embraced by oppressive regimes is a dangerous and sinister step, pushing us towards a surveillance state in which our freedom to live our lives free from state interference no longer exists.'

Silkie Carlo, director of Big Brother Watch, a privacy campaign group, said the Met Police's decision 'flies in the face of the independent review showing the Met's use of facial recognition was likely unlawful, risked harming public rights and was 81% inaccurate'.

Carlo said Big Brother Watch will challenge the move, 'including by urgently considering next steps in our ongoing legal claim against the Met and the home secretary'.

Liberty's challenge against South Wales Police will be heard in the Court of Appeal in June.