(Reuters) - Illinois’ state attorney general said on Wednesday her office identified child sexual abuse accusations against at least 500 Catholic priests or clergy members not publicly named by the church, and that many of those cases were not properly investigated.

FILE PHOTO: Attorney General for the State of Illinois Lisa Madigan testifies before the House Energy and Commerce Subcommittee on protecting consumer information in Washington February 5, 2014. REUTERS/Gary Cameron

Lisa Madigan, who leaves office at the end of the year, made the disclosures in a blistering report into an investigation she opened in August into sexual abuse in the state’s six Roman Catholic dioceses.

“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 a 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,” she said.

Madigan opened her investigation following the release of a probe by the attorney general of Pennsylvania that found Catholic priests in that state had sexually abused thousands of children over a 70-year period, crimes that were systematically covered up by bishops.

“I want to express again the profound regret of the whole church for our failures to address the scourge of clerical sexual abuse,” Cardinal Blase Cupich, archbishop of Chicago, said in a statement issued in response to Madigan’s report.

“It is the courage of victim-survivors that has shed purifying light on this dark chapter in church history,” he added.

Cupich said a commission was set up in the archdiocese in 1991 to investigate abuse and provide assistance to victims. He said that the church since 2002 had reported all allegations of child sexual abuse to civil authorities, regardless of whether the accused was alive or dead.

In her report, Madigan said the 500 priests and clergy members her office had identified were in addition to 185 publicly named by the six dioceses.

“The investigation has revealed that allegations frequently have not been adequately investigated by the dioceses or not investigated at all,” she said. “In many cases the church failed to notify law enforcement authorities or Department of Children and Family Services (DCFS) of allegations of child sexual abuse.”