Property firms which buy land as an investment and fail to develop it would face tough penalties under a Labour government in a drive to raise levels of house-building.
They could receive heavy fines or tax demands from local councils and even the threat of compulsory purchase orders as a way of forcing them to develop the land.
Ed Miliband, the Labour leader, will claim Britain is in the grip of its worst housing crisis for a generation, exacerbated by unscrupulous developers hoarding land in the hope that its value will grow because of property shortages.
Across the country, planning permission has been granted for 400,000 homes which are yet to be built and in London 45 per cent of undeveloped land is held by companies that do not carry out construction work.
At the same time demand for property is outstripping supply – about 100,000 homes will be built this year in England, about half the number needed.
In a speech tomorrow to the party’s national policy forum, Mr Miliband will signal that house-building would be a key priority for an incoming Labour government and announce that developers would come under pressure to “use or lose” the land they have accumulated.
Options being considered include giving councils the power to fine companies that own swaths of undeveloped land or to require them to pay council tax or a “land tax” on undeveloped areas. As a last resort developers who refuse to build could find themselves facing a compulsory purchase order.
Mr Miliband will say: “We have to be willing to confront some of the obstacles to house-building.
“Across our country there are firms sitting on land waiting for it to accumulate in value and not building on it – landowners with planning permission who simply do not build. We have to change that… permission to build should mean landowners build.”
The Labour leader will argue that the move would instantly mean more homes being built without an extra cost to the taxpayer, providing a shot in the arm to the economy and creating jobs.
He will point to research by the housing charity Shelter which concludes that it can take couples up to 11 years to save the deposit for a home and take single people up to 30 years.
A series of initiatives have been announced by the Government in an attempt to stimulate house construction. It includes a £10bn loan guarantee scheme to encourage developers to start building, £3.5bn of which is being targeted at housing associations to build properties to rent out to poorer families.
* Chris Grayling, the Justice Secretary, will today be accused of “risking the public’s safety” through his plans to transfer some probation services to the private sector.
The “untried and untested” plans will fragment the supervision of violent offenders, the shadow Justice Secretary will claim.
Sadiq Khan will describe it as a “dangerous gamble” and warn: “Failure could mean dangerous offenders wandering our streets unsupervised, putting their - and the public’s - safety at risk”.