Green Belt land which for decades has protected fields and open space around towns and cities should be "abolished", a think tank has urged.
The call for an end to the tough planning rules that for decades have saved the countryside around London and other conurbations, came from the Policy Exchange in a study on the effects of the planning system on the UK economy.
Best Laid Plans: How Planning Prevents Economic Growth follows three previous publications in which the report's authors Alan Evans and Dr Oliver Marc Hartwich, have shown that most of the problems with the housing market - low supply, high prices, overcrowding - can be attributed to the planning system.
They conclude in this report, that the main objective of planning has been to limit the spatial extent of cities and that this artificial reduction of land supply has severe consequences for society, the environment and the economy.
Dr Hartwich speaking ahead of the report's launch said: "Political support for the policy of constraint is based on an exaggerated view of the degree of urbanisation in the UK: it is actually only about 10% urbanised. Germany for example, has a comparable population density but uses a higher percentage of land for development than the UK.
"The planning system in the UK has been intended to restrict physical development, reducing economic growth as a result.
"In particular, Labour have made it a matter of policy that 60% of any new housing should be built on so called "brownfield" sites. This policy depends on, and results in, both high house prices and higher land prices."
Shadow Secretary of State for Local Government & Communities Caroline Spelman said: "Over the last fifty years, the Green Belt has been invaluable in protecting against urban sprawl and maintaining a green lung around our towns and cities.
"Yet I am very concerned that the Green Belt is now under a sustained assault from Gordon Brown and big business who want to cover it in concrete. Abandoning national Green Belt protection would open the way to environmental destruction on an unprecedented and unsustainable scale."
