The Campaign for the Protection of Rural England (CPRE) said that green belt land around our cities was under threat as never before.

Government plans for massive housing growth in the wider South East threaten to relax the green belt that has held the line against urban sprawl for decades, the group said. Proposed new roads and airport runways cast a concrete blight over some of our finest countryside within easy reach of big urban areas.

CPRE head of planning, Henry Oliver said: "Green Belts need to be resolutely defended from these threats, yet even professional planners, who should be their strongest defenders, sometimes scoff at Green Belt as too simple and too restrictive to be a 'proper' planning tool."

And in a shock review held on the half-century anniversary, the Conservatives claim 2,500 acres of green belt are being built over each year.

Unelected regional assemblies are fast deleting Green Belt designation, says the report. 62 planning applications in Green Belts have been rubber-stamped by John Prescott and national planning rules have been changed to downgrade the status of green belt.

The Shadow Secretary for Local Government and Communities, Caroline Spelman, said, "Mr Prescott gave a guarantee that the green belt would be protected under his tenure. But in reality, under his disastrous watch, green belt protection has been erased on a whim by unelected regional bureaucrats and consistently sidelined by weaker planning rules."

A MORI poll unveiled yesterday shows 84% of people in England believe that Green Belt land should remain open and undeveloped, and that building on Green Belt land should not be allowed.

The birthday poll found wide public awareness of Green Belts. People feared the biggest threats facing them were house building, road building and other kinds of built development including airport expansion.