Almost two-thirds of people think the green belt should not be built on, according to a survey conducted as protected land faces rising pressure from housing developments.

The poll on the 60th anniversary of the policy to protect land and countryside around towns and cities from development found that 64% believed existing green belt land in England should be retained and not built on while just 17% disagreed.

The Ipsos MORI poll of 845 people for the Campaign to Protect Rural England (CPRE) also revealed support was strong among a range of groups, including people with young families, private renters, council tenants and across different income brackets.

Support for maintaining the green belt was very high (83%) in semi-rural areas, likely to be most directly affected, but was also strong (62%) in towns and cities.

The Government has repeatedly stated its support for maintaining green belt protections.

But CPRE warns that by July 226,000 new homes were proposed in green belt land, up from 219,500 homes in March, and just 81,000 homes three years ago, while the number of houses being granted planning permission has jumped in the last year.

The campaigners are calling on the Government to be more specific on the limited circumstances in which green belt boundaries can be changed through local plans and to call in, or direct local authorities to refuse, damaging developments within the protected land that are not identified in existing plans.

They also want public funding through organisations such as conservation agency Natural England and local enterprise partnerships to increase the quality of and access to green belt land.

CPRE chief executive Shaun Spiers said: "We know that the green belt is loved by the general public and supported by politicians of all parties. Yet despite this, it is under greater threat than it has been in its 60-year history.

"Over 200,000 new houses are already planned for green belt land and a growing number of think-tanks, developers and business groups are gunning for the green belt, arguing with very little evidence that we need to build on it in order to tackle the country's housing crisis.

"The green belt is a fantastic British success story of which we should all be proud. It has both protected countryside and aided the regeneration of towns and cities across England.

"It is good for people's well-being and quality of life; good for nature and wildlife; and it provides us with much of the food that we eat. Of course the country needs more homes, but we can get them without trashing the green belt."

The focus should be on suitable brownfield sites, according to the CPRE, which estimates that a least a million homes could be built on such land.

As part of its anniversary campaign calling on the Government to match its rhetoric with action to protect the green belt, the CPRE is inviting the public to submit photos and stories to a digital wall to show how they use it, to emphasise its value.

Housing minister Brandon Lewis said: "We have placed local plans at the heart of our planning system, giving local people a far greater say over the future development of their area.

"The figures released by CPRE are from potential developments that have not yet been agreed by their local communities, have not gone through the rigour of the planning system and are not planning permissions.

"We have put strong protections in place for the Green Belt, which mean that apart from land reclassified as National Park, there were 34,000 more hectares in the Green Belt in 2013/14 than in 1997."