(CNN) In yet another blow to the Catholic Church in the United States, Illinois' attorney general says the state's six dioceses have failed to disclose accusations of sexual abuse against at least 500 priests and clergy members.

Illinois' dioceses have released lists publicly identifying 185 clergy members who had been credibly accused of child sex abuse. But state Attorney General Lisa Madigan said preliminary findings in her ongoing investigation reveal that the church failed to disclose sexual abuse allegations against at least 500 additional priests and clergy members.

In many cases, the accusations have "not been adequately investigated by the dioceses or not investigated at all," Madigan's office said in a statement Wednesday. What's more, the statement added, the church often failed to notify law enforcement authorities or state Department of Children and Family Services about the allegations.

"By choosing not to thoroughly investigate allegations, the Catholic Church has failed in its moral obligation to provide survivors, parishioners and the public a complete and accurate accounting of all sexually inappropriate behavior involving priests in Illinois," Madigan said in the statement. "The failure to investigate also means that the Catholic Church has never made an effort to determine whether the conduct of the accused priests was ignored or covered up by superiors."