Housing associations have made at least £82.3m from auctioning homes in five London boroughs since 2013, according to figures seen by the Guardian. Analysis by the Labour MP for Westminster North, Karen Buck, shows that Westminster, Brent, Camden, Hammersmith and Fulham, and Kensington and Chelsea sold 153 properties at auction through Savills estate agents – with more than half in Westminster where sales totalled £36.4m. The true figures are likely to be much higher as the data only covers sales made by one agency. The auctions are part of a wider trend of some housing associations selling off social housing in expensive central London to fund new developments, which tenants say are unaffordable or far removed from their families, schools and work.

Buck says: “I’m dealing with a family who are statutorily overcrowded and in the highest medical priority and I haven’t been able to get them moved in over eight years. That’s because housing associations [in general] say they don’t have the stock in the area and yet they’re still selling off homes.”

Nationally, sales of housing association social homes to the private sector have more than tripled since 2001, with 3,891 social homes sold in 2016. Overall, more than 150,000 homes for social rent have been lost since 2012.

Bucks’ analysis shows that in Kensington and Chelsea housing associations made £5.3m from auctions in 2013 alone. Between 2013 and 2018, Brent sold £20.9m, and Hammersmith and Fulham £13.7m.

Although most auction lots do not state the housing association selling the property, Buck has identified many homes as stock of Genesis and Notting Hill Housing, which merged in April . Notting Hill Genesis manages 65,000 homes. A spokesman says before the merger, the two associations sold 497 homes between them in the past five years, using the proceeds to build more homes in less expensive areas in and outside London. Of these, 49 were auctioned last year, raising £19.7m, but the merged housing association “will limit sales to no more than 20 per year”.

The selloffs are fuelling overcrowding and homelessness, and undermining efforts to tackle the housing crisis, experts say. “They’re buying and leasing homes all over London as temporary accommodation yet housing association homes within these boroughs are being sold off,” says Steve Hilditch, former head of policy for Shelter and a housing adviser to the last Labour government.

Meanwhile, other housing associations are redeveloping their stock. In Kensington and Chelsea, local residents and the council have warned a public inquiry that backing plans to redevelop the Sutton estate, near the King’s Road, would give housing associations across the country carte blanche to not update social housing and replace it with private homes, which risks pushing thousands of tenants into temporary accommodation or homelessness. England’s largest housing association, Clarion Group, wants to demolish the red-brick Edwardian mansion block estate. The plans have fomented debate over the provision of social housing in Kensington and Chelsea, a year after the Grenfell fire in the north of the borough. Although there are around 200 vacant flats on the Sutton estate, many survivors are still living in temporary accommodation. Clarion has said the empty homes were not fit to be let.

Campaigners argue that if Clarion had better maintained the estate they could have provided more suitable permanent accommodation for Grenfell survivors. But Kensington and Chelsea council has also come under fire for failing to house enough people made homeless after the fire.

A spokesman for the council says it has spent £235m on securing 307 properties to help rehouse people affected by the fire. Of the 203 households requiring rehousing, 134 have a new permanent home, while 52 are in temporary and 15 in emergency accommodation.

But a report published this week by the North Kensington law centre, says many homes lay unoccupied for months due to damp, disrepair and access issues. Labour MP for Kensington and Chelsea, Emma Dent Coad, says: “We have heard they [the council] are reselling some of the properties bought in haste last summer,” she adds. “We have 30 [Grenfell] households including at least one person with disabilities, and only three homes with disabled access – and it seems these may not be of the right size.”

The planning inspectorate is due to submit a report on the Sutton estate inquiry to James Brokenshire, secretary of state for housing, communities and local government, in late August. The minister is expected to make a decision on Clarion’s appeal by the end of the year.

says if the appeal is successful “it opens the floodgates to privatise social housing”. “This is a test case for social housing across the UK because if Clarion are allowed to do this, every other housing association will do the same. They’re a housing charity fighting to privatise charitable housing.” Kim Taylor-Smith, deputy council leader and lead member for Grenfell and housing, agrees. “It’s my view that Clarion’s intent from day one was to make money from the Sutton estate,” he says. “But William Sutton’s motivation was to provide homes for the poor. I would hope that they remember that.”

Clarion has also last month submitted a revised regeneration scheme for the Sutton estate to the public inquiry, which the council accepts would not lead to a loss in social housing. But it has not withdrawn the original scheme and both will be assessed by the planning inspectorate. “We remain committed to the regeneration of the Sutton estate and to providing our current and future residents there with good quality homes,” says a spokeswoman. “No further decisions will be made until the outcome of the appeal is known.”

But Clarion told the public inquiry that if its appeal against the planning decision is rejected, it would rent out the empty flats privately, noting that it had already rented out three of them, or would sell off the whole estate. The housing association adds that the empty flats cannot feasibly be renovated and re-let as social housing because they do not meet the government’s minimum standards for public housing.

“They’re claiming they can’t refurbish them as social homes but they have refurbished and let three properties out privately for £1,800 [each] a month,” Henderson says. “Grenfell survivors have told us they would like to live here because they don’t want to live near the tower again.”