Lidl managers sparked a scandal early this year by spying on their staff, using spy video systems in stores, and in some cases even private detectives.

Several hundred pages of evidence were leaked to Stern magazine, showing records were kept of when members of staff were going to the toilet, assessments of their personal appearance and even details of private telephone conversations.

At least eight Lidl shops were involved in breaking privacy rules, largely in Lower Saxony and other northern regions.

Data protection officials in North Rhine Westphalia alone are set to impose five fines for spying, unauthorised video surveillance or long-term data preservation. Three further fines are due from that state because Lidl failed to appoint its own data protection representative.