VATICAN CITY (AP) — A longtime aide distanced Emeritus Pope Benedict XVI from a new book on priestly celibacy Tuesday and asked that Benedict be removed as co-author after the project gave the impression the retired pope was trying to interfere with the reigning one.

Benedict’s longtime secretary, Archbishop Georg Gaenswein, told Italian and German media there had been a “misunderstanding” with the other co-author and that Benedict never intended to have his name on the book, “From the Depths of Our Hearts.”

Advance excerpts of the book, which is set to be published in France on Wednesday and in the United States next month, had set Catholic social media abuzz, fueling conservative-progressive battle lines that deepened after Benedict’s 2013 retirement paved the way for Pope Francis’ papacy.

While Benedict knew Cardinal Robert Sarah was planning a book and contributed text reaffirming the “necessity” of priestly celibacy, “he never approved a co-authored book and never saw or authorized the cover” giving him lead author status, Gaenswein said in a statement carried by German Catholic news agency Kathpress and Italian ANSA news agency.

Gaenswein said Benedict has asked that his name and photo be removed from the cover as well as from what was said to be a joint introduction and conclusion reaffirming the need for priestly celibacy.

Benedict’s association with the book was surprising since he had vowed to live “hidden from the world" when he stepped down as pope, specifically to avoid any suggestion that he still wielded papal authority.

The timing of the book's publication also looked suspect to Francis' supporters. Francis has said he will publish a document in the coming weeks that is expected to touch on whether married men could be ordained priests in the Amazon, to deal with a priest shortage there.

The book includes an introduction and a conclusion, said to be written jointly by Benedict and Sarah, as well as a chapter apiece. The Associated Press obtained galleys of the English text after the French daily Le Figaro published excerpts Sunday.

Earlier Tuesday, Sarah reproduced letters from Benedict making clear the 92-year-old ex-pope had written the text and approved of publishing it as a book. He spoke out after news reports quoted “sources close to Benedict" as alleging that Sarah had manipulated the pope into publishing the book.

“These defamations are of exceptional gravity," Sarah, who heads the Vatican’s liturgy office, tweeted at one point as the scandal grew.

While insisting on the transparency of his interactions with Benedict, Sarah tweeted, “Considering the polemics provoked by the publication of the book ‘From the Depths of Our Hearts,’ it has been decided that the author of the book in future publications will be: Cardinal Sarah, with the contribution of Benedict XVI. However, the complete text will remain absolutely unchanged.”

After the first reports, Francis’ supporters quickly alleged Benedict had been manipulated by members of his right-wing entourage into writing something that amounted to a frontal attack on Francis. Some claimed it was evidence of elder abuse, given Benedict's age and increasing frailty.

Conservatives, many of whom long for Benedict's orthodoxy, argued it was no such thing and noted that Francis too has reaffirmed the “gift” of priestly celibacy.

The Vatican tried to tamp down the furor by insisting the book was a mere “contribution" to the discussion about priestly celibacy written by two bishops in “filial obedience" to Francis.

Sarah — a hero to liturgical purists and conservatives and a quiet critic of Francis — denied there was any manipulation on his part and said Benedict was very much a part of the process.

He tweeted three 2018 letters from Benedict making clear the retired pope had provided him the text and participated in discussions about publishing it. In a statement, Sarah chronicled all his interactions with Benedict and said the retired pope had approved the final text, including the joint introduction, conclusion and cover.

“From my side, the text can be published in the form you have foreseen,” read a Nov. 25 letter from Benedict to Sarah.

Sarah acknowledged he had warned Benedict that his participation in the project might create a media storm, but persuaded him it was worthwhile.

Quoting his own correspondence to Benedict, Sarah wrote: “I imagine that you might think your reflections might not be opportune because of the polemics they might provoke in newspapers, but I am convinced that the whole church needs this gift, which could be published around Christmas or the start of 2020."

Sarah said he forgave all those who had defamed him by accusing him of manipulating Benedict, and affirmed his obedience to Francis.

The U.S. publisher of the book, Ignatius Press, which has been Benedict's English-language publisher since before he became pope, has defended the book and Benedict's participation in it.

The Rev. Joseph Fessio, Ignatius' founder and editor, said he had read the text in French and English, and said only Benedict could have written it.

“Is it really believable that Sarah would perpetrate a fraud?" Fessio asked in an email. “Or alter something from Benedict? Or claim that Benedict didn't collaborate and agree to the intro and epilogue?"

Ignatius in November published another book by Sarah, “The Day is Now Far Spent," in which the cardinal defended priestly celibacy.