A system being developed in the US to protect critical infrastructure by inspecting networks for evidence of cyber attacks was described as “Big Brother” by the defense contractor that is building it, according to the Wall Street Journal.

The comparison was made in an internal email from within Raytheon the newspaper claims to have seen.

The system, dubbed “Perfect Citizen”, is designed to allow the country’s National Security Agency to detect early warnings of a cyber attack on such key infrastructure as the electricity grid or power stations, it is reported. It will work by inserting sensors into the computer networks supporting this infrastructure.