Criminals convicted of gun crimes in New York City would have to register and update their addresses — similar to sex offenders — under a law proposed by city officials on Monday.

The gun registry act is one of several modest measures that Mayor Michael Bloomberg wants to push through the City Council as part of his effort to crack down further on illegal firearms. The city and state already have tough gun laws on the books.

The registry would require offenders convicted of criminal possession of a weapon in the third degree to list their addresses and check in every six months, for four years after their convictions.

Bloomberg said hundreds of people are convicted of these offenses each year in New York City, and deserve heightened supervision "because as a group they are highly prone to committing repeat violent crimes."

The council also will seek to ban gun painting kits that are used to make real firearms look like toys.

Bloomberg and Police Commissioner Raymond Kelly said guns painted in playful fluorescent colors endanger police officers who must assess risk in a split second when they are faced with someone brandishing a weapon.

Kelly did acknowledge that no painted guns are believed to have been used in city crimes or recovered by law enforcement officials, but said they learned of the paint kits through advertisements in gun enthusiast magazines.

To illustrate the danger, Bloomberg waved two handguns above his podium at the City Hall news conference, one real and one fake, but both painted like toys.

"Just imagine the tragic consequences of this kind of sick deception," he said.

Gun control has become one of Bloomberg's top priorities in his second term. The Republican mayor lobbies for the cause on Capitol Hill, and has formed a coalition of his counterparts from dozens of U.S. cities to push for stricter federal and state anti-gun laws.

The National Rifle Assocation's chief lobbyist, Chris W. Cox, said a gun offender registry is unnecessary because the criminal record system essentially serves the purpose of tracking felons. And banning paint kits, Cox added, "is not going to bring down crime rates."