The firm faced criticism in the US before Christmas from Senator Charles Schumer which put a halt to trials of Path Intelligence’s FootPath technology in shopping malls in California and Virginia.

Schumer was particularly irked by the fact that shoppers could only opt out of being tracked by switching off their mobile phones when entering the malls.

Now Big Brother Watch is on the case in the UK. Director Nick Pickles said: “We have been assured [by Path Intelligence] that no personal information is collected, and that it is impossible to connect their data with the identity of handset owners, even at the request of the police. The company has reassured us that they only supply aggregate data on an hour-by-hour basis, and refuse to disclose individuals movements or provide real-time information.

“While these safeguards are to be welcomed, we would be far more comfortable with an opt-in system, as ultimately the details of your movements are personal information.”