Wandsworth has pledged to fight any relaxation of planning laws that will threaten the character of the area or blight neighbouring homes.
Earlier this month David Cameron announced plans to allow home-owners to build bigger extensions without the need for planning application.
Richmond and Sutton have already blasted the proposals and now the leader of Wandsworth council has added his voice to to their concerns.
Under the proposals terraced and semi-detached houses could be extended for up to six metres without needing planning consent, while detached houses would be allowed extensions up to eight metres.
The Government believes the move could provide a welcome boost to the failing housing industry, as well as allow first time to get a foot on the ladder.
Wandsworth Council plans to launch a consultation on the issue soon, and Councillor Ravi Govindia, said: "Wandsworth is a residential area and most houses have relatively small gardens.
"In many, many cases a six to eight metre extension would have a severe impact on neighbouring properties and those households must be protected.
"While this proposal may provide a boost to parts of the building industry it’s unclear whether the benefits would outweigh the damage done to our neighbourhoods and neighbour relations.
"In the meantime we want to assure local people that this council will resist any changes that threaten to undermine the character of our streets or allow building works that would blight neighbouring homes."
Central government are set to launch a consultation on the plans.
Visit communities.gov.uk for more information.
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