Scotland Yard is getting its first permanent facial recognition cameras in London. Campaigners have described the move as "dystopian", but police chiefs insist they will make combatting crime easier. The cameras work by scanning faces and matching them to a database of criminals. Faces that don't match are wiped from the system.

Mobile facial recognition cameras mounted on vans have already been used by police, but new kit is to be fixed to lampposts or buildings in Croydon, south London. They will only operate when officers are available to match scans to the database, according to LBC.

Mitch Carr, the Metropolitan Police’s neighbourhood policing superintendent for south London, wrote to community figures earlier this month to announce the move.

He is quoted by The Times as writing: "It will remain the case that the cameras are only switched on when officers are deployed on the ground ready to respond to alerts".

Shadow Home Secretary Chris Philp told the same publication use of fixed facial recognition cameras is the logical next step in rolling out the technology.

He said: "Over the past year the mobile vans have caught around 200 wanted criminals in Croydon including at least two rapists who would not otherwise have been caught.

"Those few people opposing this technology need to explain why they don’t want those wanted criminals to be arrested."

Mr Philp claimed there were no "legitimate" concerns around privacy, pointing to the deletion of images of anyone who isn't wanted by police.

The MP for Croydon South said he strongly supports the move, adding: "This technology has the potential to revolutionise crime fighting in the same way that fingerprints and DNA have in the past."

Rebecca Vincent, interim director of the privacy campaign group Big Brother Watch, said: "We are alarmed by reports Croydon police are installing an unprecedented permanent network of fixed live facial recognition cameras across Croydon town centre, which marks a worrying escalation in the use of LFR (live facial recognition) with no oversight or legislative basis.

"It’s time to stop this steady slide into a dystopian nightmare and halt all use of LFR technology across the UK until legislative safeguards are introduced."

A Scotland Yard spokesperson said: "The Met is committed to making London safer, using data and technology to identify offenders that pose a risk to our communities."

They added that last year the force made over 500 arrests using LFR, removing "dangerous individuals" suspected of serious offences, including strangulation, stalking, domestic abuse and rape.

The spokesperson said: "We continue to engage with our communities to build understanding about how this technology works, providing reassurances that there are rigorous checks and balances in place to protect people’s rights and privacy."