Expensive social housing should be sold off to fund a wave of new house building, a report has urged.
Putting the highest value properties on the market when they become vacant would generate £4.5 billion to build up to 170,000 social homes a year, according to Policy Exchange.
The influential think-tank, set up by Conservative MP Nick Boles who is a key ally of Prime Minister David Cameron, claims the move could reduce the housing waiting list by up to 600,000 in five years.
Its report, Ending Expensive Social Tenancies, says that properties worth more than the average house price for an area account for one in five of the social housing stock.
The 816,000 homes have a total value of £159 billion, with £71.9 billion of that in London. Around 3.5% of the buildings become vacant each year and, after debts are paid off, would raise £4.5 billion.
The report suggests that the money should be earmarked to build additional homes and recommended introducing spending floors to ensure standards are driven up in the quality of stock.
Alex Morton, report author, said: "Expensive social housing is costly, unpopular and unfair. That is why almost everybody rejects it. Social housing tenants deserve a roof over their heads but not one better than most people can afford, particularly as expensive social housing means less social housing and so longer waiting lists for most people in need."
Housing Minister Grant Shapps said: "I've been determined that we get Britain building and help the thousands of families who for years have been left languishing on social housing waiting lists.
"That's why we've introduced radical reforms, including investing £19.5 billion public and private funding into an affordable housing programme set to exceed expectations and deliver up to 170,000 homes, and giving councils the flexibility to offer fixed-term tenancies to new tenants to ensure the precious resource of social housing goes to those in greatest need.
"On top of this, councils looking to sell vacant social housing can now keep the receipts to invest in affordable housing, regeneration or paying down housing debt in their area. And the reinvigorated Right to Buy is helping existing council tenants realise their dream of home ownership with increased discounts of up to £75,000, and for the first time a commitment to replace additional council homes sold with new affordable homes for rent on a one-for-one basis nationally."