VATICAN CITY -- Retired pope Benedict XVI never agreed to appear as the co-author of a controversial book on priestly celibacy, his personal secretary, Archbishop Georg Gaenswein, said Tuesday.
It was a remarkable disavowal of a work seen by many as both an attack on Pope Francis' authority and a serious breach of Benedict's promise to remain "hidden to the world" following his retirement in 2013.
In the book, Benedict is presented as arguing against a relaxation of the celibacy rule for priests, wading into a topic on which Francis is due to make a decision within a few weeks.
Gaenswein told the ANSA news agency that Benedict knew that Cardinal Robert Sarah was writing a book on the subject and sent him an essay on priesthood "authorizing him to do what he wanted with it."
"But he never authorized any project for a co-authored book nor had he seen or authorized the cover," Gaenswein added, calling the incident a "misunderstanding" in which Sarah acted "in good faith."
Benedict has asked to have his name removed as co-author, Gaenswein said. Sarah tweeted separately that the work would now be presented as written by him "with the contribution of Benedict XVI."
The book is called "From the Depths of Our Hearts: Priesthood, Celibacy and the Crisis of the Catholic Church" and comes out in France on Wednesday. An English version is due on Feb. 20.
Earlier Tuesday, Sarah maintained he had discussed it with Benedict several times, and characterized press reports that the book was coming out without Benedict's consent as "extremely despicable."
The cardinal, a leading conservative figure, said he urged Benedict to have his say on priesthood and celibacy despite the risk of controversy because "all the Church needs (the) gift" of his words.
The book was supposed to have had an introduction and a conclusion co-signed by Benedict and Sarah, and two separate essays by each of them.