The decline in areas not covered by the technology was significantly less, Edwin Poots added.

In the 2002/03 financial year there were 169 serious collisions at the sites, last year only 76.

Mr Poots said: "These are significant reductions and a clear demonstration that safety cameras, both fixed and mobile, reduce fatal or serious injury collisions."

The Northern Ireland safety camera scheme was launched in July 2003. As part of the first phase there were four fixed camera sites, 31 mobile camera sites and 33 mobile camera routes.

Data was collected over the three years immediately prior to the launch and compared with the three years subsequent to the launch, the Democratic Unionist minister told Sinn Fein MLA Paul Maskey.

Neil Greig, director of research and policy at the Institute of Advanced Motorists, said there was an encouraging impact in the years following the roll out across the UK.

"In the first few years they do tend to deliver but as the road gets safer there are fewer incidents so you don`t make the huge savings but you are managing traffic at a safer level," he said.

He said a camera's impact was likely to be localised and did not necessarily spread across an area.

"You do need to have a long-term plan that would involve more expensive engineering work. If you are protecting a junction a safety camera can be put in quickly but long-term you should be looking at engineering those problems out," he added.