An increasing number of companies are ‘electronically tagging’ staff in warehouses and distribution centres, a report has revealed.

The report, by Durham University for the GMB general union, found that Tesco, Sainsbury, Marks and Spencer and Boots, among others, were asking staff to wear electronic tagging.

The tags, which can be worn on the wrist, arm, fingers or a vest, instruct workers where to collect goods from warehouse shelves.

Retailers said that the tags are designed to cut costs and increase the efficient delivery of goods, although unions argue that they monitor staff and turn workplaces into “battery farms”.