Sports Direct, Spar, Budgens, Costcutter and Southern Co-op are now among the growing number of British retailers using a controversial Chinese state-owned facial-recognition system. The biometric cameras work by scanning the faces of shoppers so they can be checked against a database of suspected criminals. But they have been branded'Orwellian' and'unlawful' by critics, who claim that staff could add people to a secret'blacklist' without them knowing. So how does the facial-recognition system work, and which shops are already using it? Here, MailOnline breaks down everything you need to know about the controversial technology.

Co-Op is facing a legal challenge to its'Orwellian' and'unlawful' use of facial recognition cameras. Privacy rights group Big Brother Watch claimed supermarket staff could add people to a secret'blacklist' without them knowing. But Co-Op says it is using the Facewatch system in shops with a history of crime, so it can protect its staff. Big Brother Watch said the independent grocery chain had installed the surveillance technology in 35 stores across Portsmouth, Bournemouth, Bristol, Brighton and Hove, Chichester, Southampton and London. It claimed staff could add individuals to a watch-list where their biometric information is kept for up to two years.

Branches of Co-op in the south of England have been using real-time facial recognition cameras to scan shoppers entering stores. This story originally appeared on WIRED UK. In total 18 shops from the Southern Co-op franchise have been using the technology in an effort to reduce shoplifting and abuse against staff. As a result of the trials, other regional Co-Op franchises are now believed to be trialing facial recognition systems. Use of facial recognition by police forces has been controversial, with the Court of Appeal ruling parts of its use to be unlawful earlier this year.

Branches of Co-op in the south of England have been using real-time facial recognition cameras to scan shoppers entering stores. In total 18 shops from the Southern Co-op franchise have been using the technology in an effort to reduce shoplifting and abuse against staff. As a result of the trials, other regional Co-op franchises are now believed to be trialling facial recognition systems. Use of facial recognition by police forces has been controversial with the Court of Appeal ruling parts of its use to be unlawful earlier this year. But its use has been creeping into the private sector, but the true scale of its use remains unknown.