Cellular phone users have been asked to switch their units off at Shell service stations for fears that they may cause explosions.

Posters and flyers warning motorists of the potential dangers have been distributed to stations Island-wide.

And it was revealed that the action had been spurred on by an explosion in a United States gas station, which was believed to have been caused by sparks inside a phone, generated during its operation.

A customer warning notice said in bright red letters: "Caution. Cellular phones can ignite fuel vapour.'' It explained that the devices "emit electrical energy when they transmit'' and that this energy "can be picked up by metal objects and under certain conditions can cause sparking in or on those metal objects''.

"If such a spark occurs as someone is drawing fuel from a pump,'' the flyer continued, "it is possible that a fire or explosion could follow.'' It also stated: "Ordinary portable phones are not designed to be used in close proximity to a flammable atmosphere. If a cellular phone is accidentally dropped on the floor, its internal batteries may cause a spark, and since petrol vapour tends to collect at floor level once again -- conditions could be right for a fire or explosion.'' Asked why it was only now that such action had been implemented, Shell Companies of Bermuda operations manager Stanley Marshall said: "There was an explosion in a service station in the US which they related back to the use of a cellular phone. As a result of that Shell's head office decided to take precautionary measures to make sure such an incident doesn't happen again.'' Mr. Marshall added: "It's just a safety warning, pretty much like the one's they have on planes.'' Switch them off: Shell Bermuda representative Charlie Williams puts up a warning poster at the Blue Hole Hill station.