One of the county camera's was riddled with pellets in November

Motorists Against Detection (MAD) said it vandalised around six cameras in the county, leading to a repair bill of �100,000.

A spokesman said the group had hundreds of active members, "responsible grown-up people", who had damaged about 600 cameras over the years.

He said: "The main motivation is to draw attention to where there are problems.

It is only a matter of time before they are caught Norfolk Police spokeswoman

"We don't completely disagree with cameras, it's just the reasons they used."

The spokesman, who calls himself Captain Gasto after a type of camera, said MAD supported cameras in built-up areas but opposed them on trunk roads and motorways.

Norfolk Casualty Reduction Partnership, which operates the county's 15 cameras, said repairs to the vandalised cameras had cost �100,000.

Spokesman Bryan Edwards said serious injuries had been cut by more than 50% in the past 12 months in areas where there were cameras.

A Norfolk Police spokeswoman said: "This criminal activity is the work of a tiny minority of irresponsible people who are endangering the lives of the public and it is only a matter of time before they are caught."