Alarmed by the way authorities confiscated guns in New Orleans after Hurricane Katrina, the National Rifle Association called on all police chiefs and mayors Thursday to sign a pledge that they will never forcibly disarm law-abiding citizens.

"Mayors and police chiefs have already sworn to uphold the Constitution of the United States in their oaths of office. So signing this pledge should be just as effortless," NRA executive vice president Wayne LaPierre said a day before the group opens its annual convention in Milwaukee.

The nation's most powerful gun lobbying group also said it would support state and federal legislation making it a crime to forcibly disarm law-abiding citizens.

"We need this legislation because Katrina blew a hole in the Constitution that will continue to hemorrhage until we stop it," said Chris W. Cox, an NRA lobbyist.

After Katrina hit New Orleans, police and soldiers confiscated guns from some evacuees and removed them from homes. The police said that they took only guns that had been stolen or found in abandoned homes.

In April, police began returning some of the weapons after being sued by the NRA and other groups. They claimed the confiscations took away people's means of protection amid the lawlessness that broke out in the storm's aftermath.