Motoring assistance firm GEM is claiming 'thoughtless positioning' of sat nav devices on windscreens is posing a 'huge threat to road safety'.

According to the company, today’s large screen devices positioned in the middle of a car windscreen mean a potentially lethal reduction in driver visibility, especially on left hand bends and at junctions.

GEM chief executive David Williams said: “Sat nav devices are great for relieving a lot of motoring stress. But if in the process you’re obscuring a vast swathe of your field of view, then you are taking a huge risk.

“A typical large screen sat nav device measuring nearly seven inches (17cm) wide by four inches (10.48cm) high has the potential to cause significant restrictions to a driver’s field of view, especially if it’s mounted in the centre of the windscreen below a large rear view mirror.

“A small screen device may seem to be only a minor obstruction from inside the car. However, it has the potential to hide a much larger area outside the car, depending on where you sit and the distance you are from it.

“Placing a sat nav right in the centre of the windscreen will block most of your nearside view, and will mean you miss all the hazards that might be there. This is particularly dangerous on left hand bends, at junctions and crossings, and in any locations where you may share the road space with cyclists and pedestrians.”