There are over a quarter of a million houses planned to be built on the Green Belt despite the Government's manifesto commitment to protect rural spaces, new research reveals.

The Campaign to Protect Rural England (CPRE) has published a study today showing 275,000 houses are planned for England's Green Belt, an increase of 50,000 on last year and almost 200,000 more than in 2012.

The findings, published in the Green Belt under siege report, were compiled from draft and adopted local plans and bring into question the Conservative's 2015 manifesto pledge to 'protect the Green Belt'.

The CPRE discovered Green Belt boundaries are being changed to accommodate housing at the fastest rate for two decades. In the year to 2015, 11 local authorities finalised boundary changes to accommodate development.

A loophole in planning guidance is also being used, the CPRE reports, by local authorities to weaken Green Belt planning. Councils, under pressure from Whitehall to build more houses, are releasing Green Belt for new development through a misappropriated 'exceptional circumstances' clause.

Paul Miner, planning campaign manager at the CPRE, said: 'Councils are increasingly eroding the Green Belt to meet unrealistic and unsustainable housing targets.'

Mr Miner also called for more protection for the country's Green Belt and urged the Government to focus on brownfield sites.

To build the affordable homes young people and families need, the Government should empower councils to prioritise the use of brownfield sites. Brownfield land is a self-renewing resource that can provide at least one million new homes,' he said.

Last week, Birmingham Council was given the go-ahead to build more than 6,000 new homes on green belt land due to housing shortage.