City accountancy giant PwC is cracking down on staff who work from home too often with a 'traffic light' system that tracks their movements.

Bosses are monitoring whether employees are spending the required three days a week – or 60 per cent of their time – either out with clients or in the office.

The firm will track how often workers swipe their security passes in the office and when their phone or laptop is connected to a client's wifi network.

If they fall below the 60 per cent threshold, an amber light flashes on their screen, switching to red if they drop below 40 per cent, the Financial Times reported. Staff, who are said to be unhappy with the new system, then face being sanctioned at appraisals or having their bonuses cut.

One senior employee said they had 'lost count' of the number of colleagues who had raised concerns about monitoring, while another said workers wanted more transparency as the company began 'pushing hard' to increase attendance.