The use of magnets as fastenings on outdoor clothing and phone covers could cause hillwalkers to make potentially life-threatening navigational errors, Mountaineering Scotland has warned.

The outdoors organisation is warning walkers and climbers of the risks of compass deflection and even reversed polarity caused by the growing use of magnetic closures in outdoor clothing.

Heather Morning, mountain safety adviser for Mountaineering Scotland, described a recent incident in Glen Shee, which was thought to have been caused by a magnetic fastening on a mobile phone case deflecting a compass needle, when a group of walkers headed east instead of west and became disorientated in low cloud.

Morning said: “Fortunately no one was hurt – just pride dented – but it could have turned out so much worse had mountain conditions been more severe. The reason for the error was the compass. It had been stored in a pocket next to a mobile phone in a case which had a magnetic closure on it, and the magnet had reversed the polarity of the compass needle, so that the north arrow pointed south.”

She urged those using compasses to be aware of the magnetic fields that exist around smartphones, as well as magnets hidden in mobile phone cases, cameras, car keys, belts and other fastenings.

Morning said: “Modern technology is great. The resources available now to keep us warm and safe in the mountains have never been better. But more joined-up thinking is needed between outdoor clothing manufacturers and mountain users to avoid potentially life-threatening consequences.”

Mountaineering Scotland advises walkers and climbers to keep compasses in a separate location to other electronic devices they are carrying on the hill and to ensure, when using them, that they are held well away from the body.

It also advises them to read a compass alongside a map, to ensure that the contours on the map match the compass bearing, and to always carry a spare in the event of malfunction.