A controversial covert surveillance system that records the public's conversations is being used in Britain.
The technology, called Sigard, monitors movements and speech to detect signs of threatening behaviour.
Its designers claim the system can anticipate anti-social behaviour and violence by analysing the information picked up its sensors.
Dylan Sharpe, from Big Brother Watch, said: "There can be no justification for giving councils or the police the capability to listen in on private conversations.
"There is enormous potential for abuse, or a misheard word, causing unnecessary harm with this sort of intrusive and overbearing surveillance."