THE LOS ANGELES CITY COUNCIL and Mayor Antonio Villaraigosa have inadvertently united a patchwork of neighborhood groups stretching from the Valley to Venice, whose members have joined to stop city leaders from tossing out hard-won neighborhood zoning rules that keep a lid on ­overdevelopment.

The Council and mayor, saying they were complying with a state requirement to encourage more affordable housing, recently put on the books an ordinance that allows much bigger apartment complexes in areas whose residents believed they had won the battle against overconstruction.

“They broke the law, like usual,” says Robert Silverstein, a Pasadena attorney who opposes the so-called “density bonus” that waters down existing zoning.