Four of California's leading Roman Catholic bishops, including Los Angeles Cardinal Roger Mahony, have taken the extraordinary step of urging an Australian bishop to cancel a monthlong tour of the United States to promote his controversial new book about clergy sexual abuse.

Following direction from the Vatican, the California religious leaders and eight other prominent bishops around the country have asked former auxiliary Bishop Geoffrey Robinson of Sydney to steer clear of their dioceses because of his "problematic positions" on priestly celibacy and other issues.

In his book, "Confronting Power and Sex in the Catholic Church: Reclaiming the Spirit of Jesus," Robinson argues that the church's celibacy requirement has contributed to the sex abuse crisis. He openly criticizes the papacy for failing to provide leadership. And he wonders whether the Catholic Church has been more concerned with managing the scandal than confronting it.

The dioceses said they are not trying to silence Robinson, who notified each of his plans, but to guard against what they believe is his misinformation.

Robinson said he ultimately concluded that he could not continue to serve as a bishop of a church that left him with such "profound reservations." He resigned and began to write his book, which was published last year.