City councillors were irate over the possibility of losing more affordable housing due to the recent sale of 57 low-cost housing units to a real estate trust at a session of the Cambridge City Council last night.

Grove Properties, a Connecticutbased company, is buying 929 House, an 18-story concrete high-rise on Mass. Ave. only four blocks away from Harvard Yard.

It is currently home to 43 low-and moderate-income tenants.

Grove's Chief Executive Officer, Damon Navarro, and Chief Investment Officer Marnawar A. Cheema said they plan to gradually phase out low-cost housing as tenants move out voluntarily.

"To lose affordable housing in these units is unacceptable," Mayor Francis H. Duehay'55 said. "I am very angry at this."

In recent years, Cambridge has felt the loss of affordable housing as rents rose in the wake of the elimination of rent control.

As a result, many low-income tenants are losing their rent subsidies as owners opt for higher-paying tenants.

The units were originally designated as low-cost housing in the 1970s, when federally-subsidized mortgages required owners to designate portions of their buildings for affordable housing.

Now owners are paying off those mortgages and eliminating legal requirements--which allows the owners to raise rents.

Because the mortgage was paid off when the building was sold, Grove Properties may eliminate most of the subsidized housing, except for 24 units protected permanently by Cambridge zoning laws.

Navarro and Cheema proposed reducing the number of affordable housing units to 30, leaving the rest unprotected.

They assured the council that no low-rent tenants would be evicted and that they would allow tenants in low-cost housing to remain as long as they wished to stay.

Initially, Grove Property Trust and the City of Cambridge had a verbal agreement that Grove would keep all the affordable units in exchange for a $2.3 million low-interest loan from the city, representing the difference between the market rent price and the affordable-housing price.

However, in mid-December, after presenting the proposal to their board of trustees, Grove told Cambridge that the deal was unacceptable, angering the councillors-who are considering seizing the property from Grove in exchange for the market price.

Representative Michael Capuano (D-Somerville) appeared at the hearing to voice his support for affordable housing.

Capuano pledged to fight for affordable housingin Congress.