Campaigners pushing for an area around Norwich to be formally designated as green belt say a new national report has strengthened their call.

The Norfolk branch of the Campaign to Protect Rural England (CPRE) launched a 'Green Belt for Norfolk' petition at www.change,org earlier this year, which is just shy of 1,000 signatures.

A green belt does not forbid development, but aims to preserve the character of historic towns and assist urban regeneration.

Members of CPRE Norfolk said the risk of developments 'springing up' was greater than ever as work progressed on the Northern Distributor Road dual carriageway from the A47 at Postwick to the A1067 north of Taverham.

And the charity says new research it commissioned from environmental consultants ADAS, shows the 'huge potential' of the green belt in terms of amenity and nature conservation.

The report, published today, specifically mentions Norwich.

It says the area is at 'exceptional risk of losing valuable urban fringe countryside to sprawl'.

The charity is calling on the government to prioritise investment in green belts in the forthcoming 25-year plan for the environment and make sure protection is enforced.

Helen Leith, branch director for CPRE Norfolk, said: 'This major new report examines the benefits of green belt land and strengthens our Norfolk branch's call for a green belt around Norwich.'

Government green belt policy was established in 1955 primarily to stop urban sprawl, but the nearest designated green belt to Norwich is in Cambridge.

Christopher Dady, chairman of CPRE Norfolk, previously said: 'One of the issues we see in Norfolk is the city of Norwich and towns and villages being allowed to sprawl outwards, to the detriment of the countryside and the urban environments.

'This should not happen when there are opportunities to develop brownfield sites and bring empty buildings back into use, faster and more cheaply than building on green field sites.'