The number of new homes being built on garden space has doubled since Labour came to power, it was claimed today.

Conservative MP Greg Clark said 11% of new dwellings were built on previously residential land in 1997, but the figure stood at 22% by 2006.

Levels of "garden grabbing", in which property developers buy up family homes with gardens and typically replace them with apartment blocks, had jumped from last year's figure of 18%.

The figures, contained in a written answer to Mr Clark from the Department for Communities and Local Government, showed London saw the biggest annual rise in building on gardens from 16% in 2005 to 29% in 2006.

He accused the Government of holding back the data until after the local and London mayoral elections, during which time Boris Johnson campaigned against the practice of garden grabbing in the capital.

The figures also showed south east England was suffering the most acute loss of gardens, with 32% of new homes from previously residential land in 2006.

The East of England and East Midlands were also suffering big rises in garden grabbing, Mr Clark said.

He said: "These figures prove more and more gardens are being bulldozed under Labour.

"Ministers have ruthlessly exploited the absurd situation in which gardens are classified as brownfield land.

"This is how they achieve their brownfield development targets - not by regenerating derelict land, but by destroying green space in our towns, cities and suburbs."

A Private Member's Bill introduced by Mr Clark in 2006 to exempt gardens from the definition of brownfield sites was not passed in the last session of Parliament but had been adopted as Conservative policy.

But Iain Wright, Housing Minister, accused the Conservatives of being "disingenuous".

He said: "These figures include conversions and the replacement of run-down houses and estates. Only a fraction involve development on back gardens.

"We are building more homes than ever before on former industrial sites to protect green spaces."

He went on: "What Tory hypocrites on this issue don't admit is that gardens have been classified as brownfield sites since the 1980s and that councils have been given strong powers to prevent 'garden grabbing'
by Labour.

"Local councils, many of which in London and the South East are Tory controlled, make these decisions and they have always had the power to turn down applications for inappropriate housing development in back gardens."