By Mike Lloyd For BBC News Online Scotland

Housing policy has been questioned

A report from Heriot Watt University in Edinburgh has suggested that hundreds of millions of pounds of public subsidies have been misdirected.

"The geographical distribution of net need is quite different from the current distribution of actual social housing investment," Professor Glen Bramley's study has argued.

The report came as housing organisations step up criticism of the Scottish Executive for failing to replace the quarter of a million council houses sold in the last 10 years with new affordable homes.

My model suggests the need for affordable housing is greatest, not in west central Scotland, not in Dundee, but in areas of high house prices Prof Glen Bramley

Alan Ferguson of the Chartered Institute of Housing, recently called on the executive to act over the "shocking" lack of affordable housing.

Campaigners from Shelter described the new probe as "a reminder that amid the fever of rising house prices, there are many people in Scotland who have been priced out from buying their own home."

Both organisations want the executive to make sure that low rent houses are built to provide homes for more than 170,000 people on council waiting lists.

Housing experts have suggested the current shortfall arises partly because cash has been poured into regeneration projects at the expense of affordable housing.

Researchers argue that - surprisingly - it is in prosperous parts like the Lothians, rather than deprived areas, that middle to low wage earners consequently suffer.

"If you have a job in Glasgow or Dundee, it is relatively easy for someone on an average wage to buy a house, but in the Lothians it is very difficult," Prof Bramley said.

Prof Bramley criticised policies

For many years, research has shown that overcrowding and homelessness rise when people cannot afford a place to live.

But Professor Bramley thinks the solution is not simply for the public housing body, Communities Scotland, to pour more cash into public housing.

"Communities Scotland should be redirecting some of its resources, but we also have to look at using the planning system," he insisted.

Prof Bramley wants ministers to back local councils, when they require private developers to build affordable homes as a condition of planning permission.

He also maintained that it is vital new houses are put up in the right places.

"There has to be clear evidence of need. We have to look at supply and demand."

"My model suggests the need for affordable housing is greatest, not in west central Scotland, not in Dundee, but in areas of high house prices."

The Scottish Executive said it is working "to ensure everyone has a warm, dry, affordable home."