UK drivers caught using a mobile phone, satellite navigation system or MP3 player face up to two years in prison, under new legal guidelines which come into force today.

The new guidance, which has been drafted by the Crown Prosecution Service, means that motorists will be charged with dangerous driving for using the devices in a moving vehicle.

The maximum penalty for dangerous driving is two years in prison, rather than the fine or community service order that was previously available under a charge of careless driving.

Rob Gifford, executive director of the Parliamentary Advisory Council on Transport Safety, said that the new rules would affect only those whose reckless actions led to an accident.

"It is not every single driver using a mobile phone while driving that faces jail. It is those few drivers whose behaviour leads them to have a crash when they are using a mobile at the same time," Gifford told BBC Radio 4's Today programme.

"What people are being reminded is that driving is a complicated activity and it is better to concentrate on driving than talking."