The Dutch privacy watchdog CPB has ordered a company which tracks the behaviour of people in shops by using their mobile phone signals to change its methods, saying they are breaking privacy legislation.

Bluetrace has developed equipment allowing shopkeepers to monitor what people do in their stores and how long they spend where using wifi tracking technology.

The CPB said Bluetrace is not keeping to the letter of law in the way it collates information without informing the public what it is collecting and what use the data is being put to. In addition, the company keeps information indefinitely.

The company has now said it stores the data anonymously and is wiping the information after 48 hours. In addition, it will stop recording the movements of people who walk past shops without entering.

The CPB said it will assess these new measures shortly to see if they conform to privacy rules.

Among the clients listed on the Bluetrace website are snackbar chain Febo, Gouda city council, CBRE Global Investors and Ryanair.