Tenants opposed to the social cleansing of city centres will protest outside an auction at a luxury hotel where property developers and private landlords will bid for £7.2m worth of former social flats and houses.

Nearly one in 10 of the lots, which are being auctioned by leading estate agent Savills at the Marriott hotel in London’s Grosvenor Square on Monday, are former social housing, with 14 lots being sold by housing associations and six by councils.

They include three housing association flats in Croydon, two housing association flats in Camberwell and a housing association house in Harlesden. These three areas have more than 7,000 families in temporary housing and 104 people sleeping on the streets, according to the most recent government figures.

In the last Savills auction in February, more than 15% of the lots were sold by social landlords, including a two-bed housing association flat in Bayswater sold for £603,000 and a housing association flat in Paddington belonging to a woman who was forced to move after her housing benefit was cut by the so-called bedroom tax.

These sales are part of a wider trend that has seen some housing associations sell off social housing in high-value inner city areas in order to fund new developments, which tenants claim are frequently let at close to market rents, or even sold on the open market to private buyers.

One, one of the country’s biggest housing associations, Genesis, is at the forefront of this commercial drive. The 32,000-home landlord, which operates across London, has four lots listed for sale. In February, Genesis listed 22 lots of social housing, including a two-bedroom flat in Maida Vale sold for £417,000, a one-bedroom flat in Notting Hill sold for £401,000 and a flat in Kilburn sold for £450,000.

Genesis is set to merge with neighbouring London housing association Notting Hill Housing, which is selling five flats worth more than £1.6m in the auction.

Peter Denton, a retired engineer who became a Genesis tenant 40 years ago during his wife’s terminal illness, said he was saddened by the loss of so many affordable homes. “Social housing was meant to house the poorer sector of society and should not be treated as a saleable cash cow,” he said.

Gemini Verney-Dyde, who was rehoused from a squat by Notting Hill Housing in the 1970s, said: “If you sell off central London property because of its value, you are essentially socially cleansing.

“The only people who can buy those properties are wealthy people.”

Gaynor Aaltonen, a writer, who lives in a Genesis flat in Maida Vale, said housing associations were selling London’s inheritance to the rich: “It is a great creative city – it is not just a city for bankers. But it won’t have any life any more if it all goes.”

Molly Ayton, a Genesis tenant of 39 years, said she had paid for her flat many times over with her rent: “They were helped to buy these flats with public money so they should remain as social housing.”

Genesis chief executive Neil Hadden told Inside Housing magazine in 2015 that housing people on the lowest income was not his “problem” any more as his focus was supplying homes at different price points. The company’s last annual report reveals it completed 159 homes in 2016. Of these, only three were rented at social levels, which are typically less than half the cost of market rents. In the same period, it sold 58 social homes to the private sector.

Genesis and Notting Hill tenants report that flats that were once rented to their friends and neighbours on a social housing basis in central London are now being used as profitable Airbnb rentals, rented out for at least twice the rate by buy-to-let landlords, or put on the market for £1m-plus.

Judi Wilson, who lives in a Genesis flat in Brent, said the flat below her was sold at auction a few years back and was now used as an Airbnb rental. “There is a constant turnover of guests, some of whom have held wild parties,” she said.

Peter Robinson, who lives in a Genesis flat in west London, said the two flats above him were sold after the tenants moved out: “At least 50 potential buyers so far have been shown round the flat immediately above me. Maybe the £1m-plus price tag is putting them off.”

Westminster MP Karen Buck, whose constituency includes thousands of Genesis and Notting Hill properties, said both associations were becoming developers rather than social housing providers: “Genesis and Notting Hill began life in my constituency as a response to private sector squalor and Rachman-type landlords. Both of them have lost sight of their mission to provide decent social housing in areas like Paddington.”

The auctioning of social homes was depriving her constituents of vital social housing, she added. “It sticks in my throat to see social housing sold off in a swanky hotel.”

Genesis said it was still committed to helping those who find it difficult to meet their housing needs in the marketplace. “Over time, our approach to delivering this in the most effective way has had to evolve in step with changing government policies and a difficult operating environment,” said a spokesperson. Scarce government funding had forced it to become more commercial but it was replacing social homes: “We have built far more social rent homes than we have sold.”

Notting Hill Housing said it still provided Londoners with good quality homes, and any profits from sales were invested in affordable housing. “Times have changed and the lack of government grants brings pressures, but any commercial work and property sales we undertake is done to create greater surpluses to invest in more affordable housing,” it said, adding that it sold properties in high-value areas to fund development of family homes elsewhere in London.

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 – mainly through the government’s policy of converting social rents into affordable rents and right-to-buy purchases.

•This article was amended on 26 March to make it clear that Genesis listed 22 properties in February rather than sold 23