Playboy Enterprises sued its former casino partner.

Chicago-based Playboy said it seeks to force Elsub Corp.--a subsidiary of Elsinore Corp., which owns the financially troubled Atlantis casino (formerly the Playboy) in Atlantic City, N.J.--into involuntary bankruptcy. The suit was filed in U.S. District Court in New Jersey. Christie Hefner, Playboy’s president and chief operating officer, said the suit was filed “to preserve (Playboy’s) rights and our claim to the assets of Elsinore and its affiliates.” Playboy sold its 45.7% interest in the casino last year and holds Elsub’s unsecured note for $38 million. Elsinore said last month that it was trying to restructure its public and private debt.