The British government is warning motorists of the dangers of fully trusting their satellite navigation devices with its first “Don’t trust your satnav” road sign.

The signs, introduced by authorities in rural St Hilary, in the Vale of Glamorgan, South Wales, to warn drivers about placing too much faith in the directional gadgets, could be brought in across the country if the trial is successful.

According to some media reports, problems arose after foreign drivers found it difficult to understand phrases such as “unsuitable for heavy goods vehicles” but could understand pictorial notices.

The four signs have been introduced around one particular black spot in the village, where the electronic devices direct truck drivers to a shortcut between the main M4 motorway and Cardiff airport. However, the road is far too narrow for many to travel down, causing them to get stuck and sparking major traffic problems.

Traffic Engineer, Mark Simpson said, “We have had a series of problems with drivers getting into trouble by trusting their satnavs and we needed to do something about it.” He also mentioned that more than a dozen large trucks have become stuck in the road in the past six months.

“They can send drivers on the most direct routes which turn out to be narrow roads completely unsuitable for heavy and long trucks and lorries. Satnav can be a wonderful tool for drivers but it does have its dangers,” Simpson added.

If successful, officials plan a national roll-out of the signs to combat what is seen as a growing problem for frustrated motorists, with recent figures showing that more than four million of Britain’s 32 million drivers rely on satnavs.

Some have reported that software glitches have sent drivers down one-way streets or up impassable mountain tracks. There was even an instance when one ambulance driver with a faulty satnav drove hundreds of miles in the wrong direction while transferring a patient from one hospital to another just eight miles away.

A spokesman for the Welsh Assembly regional government said that officials would be “watching closely” the trial’s results before deciding whether to expand the program.