Mr King says increasing officer numbers would reduce offences

Edmund King, from the RAC Foundation, believes an over-reliance on speed cameras means other motoring offences are going undetected by officers.

He says the decline in traffic police numbers must stop and police should be "more visibly present" on roads.

He will outline his views on Wednesday in a speech to the Police Federation Conference in Bournemouth.

Drivers 'take a chance'

Mr King will tell delegates: "The massive increase in the use of speed cameras in recent years does not by any means justify the correlating decline in numbers of traffic police.

"This increasing focus on targeting offences that can be caught on camera means that other serious offences, such as drug driving and careless driving, are going unchecked.

"We know that many people now take the chance of drinking and driving because their perception is that they will not be stopped."

Last week, the federation's national chairman Jan Berry said officers were facing anger from motorists over speed cameras and are regularly called money-grabbers.