SCOTLAND Yard has come under fire over its decision to introduce live facial recognition with human rights campaigners branding the move "dangerous, oppressive and completely unjustified”.

The Met announced that within a month it would begin to use the controversial technology - following a number of trials - to help the fight against serious and violent crime as well as also helping to find missing children and vulnerable people.

Nick Ephgrace, the force’s Assistant Commissioner, said: "Every day our police officers are briefed about suspects they should look out for; live facial recognition 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," he added.

The plan is to put suspects wanted by police or the courts on "watch-lists" and if they are spotted by the cameras, they will be approached by officers.

Trials of the cameras were used in various locations, including London’s famous West End.

The Met claimed the technology had a very low failure rate, creating a false alert only once in every 1,000 times. But, using a different metric, last year, academic research suggested the technology only had eight correct matches out of 42 in trials.

Scotland Yard stressed the public would be aware of the surveillance as the cameras would be in open locations and officers would be handing out leaflets.

However, Silkie Carlo of the UK civil liberties group Big Brother Watch, calling for the force to reconsider, denounced the move, saying: “This decision represents an enormous expansion of the surveillance state and a serious threat to civil liberties in the UK.”

Campaign group Liberty called the Met’s decision a "dangerous, oppressive and completely unjustified move".

Clare Collier, the group's Advocacy Director, said: "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."

Siobhan Benita, the Liberal Democrat candidate for Mayor of London, said: "It is unacceptable for a new form of mass surveillance like this to be rolled out onto London’s streets without proper consultation, regulation or oversight.

"Facial recognition technology is hopelessly inaccurate. It is biased against women and ethnic minorities. The evidence that it will make us safer is patchy at best, but there is a real risk that it will erode civil liberties and increase distrust and discrimination,” she added.