A national gun rights group filed suit yesterday against the U.S. Conference of Mayors and the mayors of 23 cities, contending that a flurry of recent lawsuits against gun manufacturers have harmed firearms consumers.

The Second Amendment Foundation, a lobbying group based in Bellevue, Wash., had warned for months that it would sue the cities to counter a wave of litigation aimed at the firearms industry.

The foundation's suit, filed in U.S. District Court here, accused the mayors of conspiring to illegally interfere with interstate commerce and to violate the gun-buying public's constitutional rights to bear arms and engage in self-defense.

The Shooters Committee on Political Education Inc., a New York-based gun advocacy group, joined the foundation in filing the lawsuit.

The suit names the U.S. Conference of Mayors and the mayors of Los Angeles, Miami, Chicago, Atlanta, Cleveland and 18 other cities, which have either filed suit against the firearms industry or are on the verge of doing so. The cities' lawsuits seek damages from manufacturers, dealers and shops for crimes committed with guns, arguing that taxpayers have been forced to pay medical bills and other costs.

A spokesman for the U.S. Conference of Mayors declined to comment, saying he had not seen the complaint.