Open data to encourage 'questions' about the number of council houses worth more than £1m apiece
Local authorities have been ordered to publish in-depth data about the value of their council homes - in order for the most valuable to be sold.
Eric Pickles, the communities secretary, said it was wrong for local authorities to hang onto pricey properties which could be sold to fund more affordable housing.
Now, from April, councils will be required to publish the most recent valuations of their housing stock, to "give people the information they need to ask questions".
The data must be made available by postcode, listing how much the properties are worth, how many are occupied and how many are standing empty.
Local voters have been urged to scrutinise the information and to question whether selling more expensive properties could provide funds for councils to build badly-needed accommodation.
Pickles' department highlighted how the London borough of Southwark sold a four-story, Grade II-listed building for £3 million. The sale helped to fund the building of 20 new properties in the capital, where there is an acute housing shortage and where ministers are eager to step up home building.
Pickles said: "Councils across the country are sitting on millions of pounds which could be put to far better use and get them building elsewhere in the area. Instead of holding that money as equity in expensive empty properties, the councils should sell up those vacant buildings and reinvest the money to keep the capital building.
"This would allow more families to come off social housing waiting lists and get into homes."
The move builds on the research of the Tory-leaning think tank Policy Exchange, which showed that nearly 230,000 social homes in London - with a total value of £72 billion - were worth more than the average property price in the area.
Since then, property prices in the capital have soared and there are suggestions that hundreds of social housing properties are now worth more than £1 million.
However, it is likely that the new "affordable" homes will be built at up to 80 per cent of what the local market demands, under rules introduced by the coalition.
That is much higher than the typical 50 per cent charged for "social rented" homes, which means tenants need housing benefit, say critics - pushing up the social security bill.