A South Carolina gun dealer who sued Mayor Bloomberg for saying that his shop engaged in “criminal behavior,” has asked a judge to put the case on hold so he can defend himself in an unrelated criminal case.

Licensed firearms dealer Larry Mickalis was indicted earlier this month on charges he illegally sold a rifle to an ex-convict two years ago at his pawn shop in Summerville, S.C.

The charge was a surprise development in the embattled merchant’s ongoing legal battle with New York City, and his attorneys have now asked courts in two states to freeze the civil litigation until the criminal case is resolved. One of the gun dealer’s lawyers, Scott Allan, argued in court papers filed Wednesday in New York that the stays are necessary “to avoid undermining Mr. Mickalis’ Fifth Amendment right against self-incrimination.”

A similar request has been made to a judge in South Carolina regarding parallel litigation there.

The legal fight between the two sides began in 2006, when Mr. Bloomberg sued more than two dozen out-of-state gun dealers, claiming their reckless sales practices put weapons into the hands of criminals. Outraged, Mr. Mickalis responded by suing Mr. Bloomberg for slander.

Both cases are pending. The federal judge overseeing the city’s suit and the judge in Berkeley County, S.C. presiding over the slander case have yet to decided whether to grant the freeze.

Lawyers for the city intend to oppose attempts to stay either case.

Federal prosecutors have released little information about the 2006 gun sale that formed the basis of the new criminal charge against Mr. Mickalis, but his attorney, Andy Savage, said it involved a woman who purchased a gun on behalf of a boyfriend with a criminal record.