A conservation group has told planners there is no need to build on protected green belt sites and criticised over-inflated population targets.
Sue Howie, executive director of Northumberland and Newcastle Society, claimed unrealistic population estimates could cause unnecessarily large areas to be zoned for development.
In a planning document passed last month, Northumberland County Council claimed developers had failed to keep pace with an ageing and increasing population and predicted a rise of 33,000 people by 2031.
Council leaders claimed they had little option but to “delete” large swathes of green belt around Hexham, Prudhoe and Ponteland “in order to deliver the level of economic and housing development required”.
But Mrs Howie said the figure - which equates to roughly the same population as Blyth – could lead to a “pattern of development which will be wasteful of resources”.
It comes as the National Trust waded into the green belt row to claim Government planning policy was putting the protected sites at risk.
A survey said half of the councils across the country with green belt land – including some in the North East – were preparing to allocate some of it for development ahead of brownfield sites.
Mrs Howie said: “If unnecessarily large areas are zoned for development, the housing will be dispersed and the pattern of development will be wasteful of resources.
“We feel that future development should be compact, with lively neighbourhoods and facilities and jobs which are convenient to existing and new populations, preserving the natural and historic character of the county wherever possible.
“This can best be achieved by zoning the right amount of land for development. Unrealistically high population targets have already caused widespread dismay because the county proposes to cut back the green belt in Prudhoe, Hexham, and Ponteland to allow land to be zoned for housing.
“Green belts are one of the oldest and most popular planning policies. It seems likely that if the lower 13,000 population target is adopted there would be little or no need to erode the green belt.”
Tensions are already high in rural areas of the county and elsewhere in the North East as a string of controversial developments have been proposed.
Overall, more than half of the 147 local authorities that responded to the National Trust survey said they had brownfield sites available that could help meet the five-year housing land supply target but these had not been considered viable.
The survey findings come 18 months after the Government put in place its National Planning Policy Framework, which aimed to speed up decisions and boost house building.
Local authorities are required to work out future housing needs in their area, and allocate sufficient land to meet it, with the “presumption in favour of sustainable development”.
Earlier this year, the Campaign to Protect Rural England said the number of houses that were being planned for Green Belt land has nearly doubled to 150,000 in the past 12 months.
Simon Jenkins, chairman of the National Trust, said: “Some councils may want to review their green belt boundaries as has always been possible, but the planning system as a whole should attach a greater weight to protecting green spaces.
“The Government’s definition of ‘sustainable’ is in practice being interpreted as ‘profitable’, and has effectively killed the former planning presumption in favour of brownfield land.”
Jan Bibby, regional director for the National Trust in Yorkshire and the North East, said: “We work closely with local authorities in the region, inputting into and monitoring local planning decisions.
“We believe a good balance can be struck between planning and development without impacting on green belt land.”
Planning Minister Nick Boles said: “The coalition Government has safeguarded national green belt protection, abolished Labour’s regional strategies which threatened to rip up the green belt, and introduced a new protection for valuable green spaces.”