An over-generous interpretation of brownfield sites by the Government could lead to the destruction of residential suburbs in Birmingham, with planners forced to allow mini-housing estates to be built in large back gardens.
The warning was sounded by city councillors, who said they were often powerless to prevent insensitive development which was unwanted by local communities.
David Roy, chairman of the planning committee, said the council was campaigning for a change in Government guidance, which classifies back gardens as brownfield sites and therefore suitable for residential development.
Coun Roy (Con Sutton Vesey) added: "It is an absolute nonsense back gardens are treated the same as a disused gas works. Yet the Office of the Deputy Prime Minister will not move on this."
Planning committee member Barry Henley said the council was losing the battle to save the suburbs.
Coun Henley (Lab Moseley & Kings Heath) added: "We cannot afford to have every large back garden turned into 20 flats. We are fighting to stop bowling greens turning into housing."
The council has warned of builders "cold calling", knocking on doors in Moseley, Kings Heath and Sutton Coldfield to persuade householders to sell back gardens for development. The practice has been condemned in parliament by Sutton Coldfield MP Andrew Mitchell.
City council leader Mike Whitby urged all Birmingham MPs to lobby the Government.
"We need to get this clumsy description of a brownfield site rectified," he added.
Renee Spector, a planning committee member, said the issue was far from straight-forward.
Birmingham was under pressure from the Government to build more new homes, but suitable sites were limited.
Coun Spector (Lab Erdington) added: "Where is new housing to go? We are all agreed it should not go in the green belt and I think we feel there are enough high-rise blocks of flats. But where are the families to go?
"There are some small bits of industrial land here and there which can be used. But the important question the council needs to put its mind to is where can these people be accommodated?"
Coun Spector urged her colleagues to resist pressure to build more flats in the Jewellery Quarter.
"We set a limit of 2,000 dwellings, but this has been more than reached. We have to ask ourselves if enough is enough?"