Drivers in Norwich who speed in 20mph and 30mph areas could be targeted by cameras which monitor how fast they travel through the zone.

Police and council bosses are considering whether to introduce average speed cameras to enforce limits in the city and in some of Norfolk's larger towns such as Great Yarmouth and King's Lynn.

The average speed cameras work in pairs, with one recording the number plate of drivers and starting a timer. The second clocks the car's registration as it leaves a zone and calculates the speed at which the vehicle travelled.

The possibility of using such cameras to crack down on speeding motorists is to be discussed at Norfolk County Council's environment, transport and development overview and scrutiny panel at County Hall tomorrow.

A report by council officers to members of the panel looks at new Department for Transport guidance issued earlier this year, and this includes the possibility of using urban speed cameras.

Judith Lubbock, Liberal Democrat city councillor for Eaton, has long campaigned for a blanket 20mph limit in all residential streets in Norwich.

She said: 'It's a good opportunity to engage the police in the debate over 20mph zones.

'I think people will be very encouraged if they think more is to be done to enforce these limits.

'People need to change their habits if we are to reduce the number of pedestrians and cyclists becoming casualties.

'I think public confidence in the limits would increase if there was some sort of enforcement.'

The council officers' report recommends that members consider their use, supported by the police within the Norfolk Safety Camera Partnership, as part of a range of speed management measures in urban areas such as Norwich.

It also recommends that, if the council was to move forward with the idea of average speed cameras in urban 20mph or 30mph areas, there would need to be a public consultation.

Regarding the potential impact average speed cameras could have, the report said it was likely to have a 'moderate impact on the council's ability to retain its excellent record of reducing road casualties, in particular if resources are diverted from schemes with higher casualty reduction benefits'.

It goes on to say: 'Whilst some would point to the highly effective performance of average speed cameras in managing speeds, the majority of motorists who would be detected as committing offences are likely to be from within the community whose roads would be managed.

'This raises an issue of what kind of council we wish to be perceived as: one which intervenes heavily on the side of the community to address the behaviour of individual road users; or one that encourages positive actions and attitudes without being over-bearing in its dealings with individual members of the community.'

Speed cameras in the county are managed by the Safety Camera Partnership, which involves the council and Norfolk police, and the report says, at the moment, the partnership has not identified average speed cameras as a priority.

But it said: 'The police have given a view that use of average speed cameras could be supported if the circumstances are considered to warrant their use.

'They are likely to involve high capital costs and might be expected to cover maintenance costs through the revenues generated from Fixed Penalty Notices.

'The benefits in terms of casualty reduction are unlikely to be significant; however they could offer significant community reassurance and support the wider benefits of urban speed limits.'

Norfolk police and Bev Spratt, the chairman of the council's environment, transport and development overview and scrutiny panel, said they did not want to comment ahead of tomorrow's meeting.

Norwich City Council was one the first places in the country to introduce 20mph limits in the 1990s. A self-enforcing limit was introduced at North Earlham after a young boy died after being hit by a car being driven at nearly 60mph.